Transfem

Actually that understanding is totally being reevaluated. Anecdotally, my case is a good example, but far from unusual. I never took anti-androgens and my testosterone production significantly reduced once my estrogen levels started to raise. While still only using 1 patch, twice weekly for a few months, my testosterone dropped from around an average of 400-500ng/dL to 46ng/dL. My estradiol levels at that time were still in the low 100pg/mL range. Prior to my surgery I had moved up tp using 3 patches my to bring my estradiol levels to the low 200pg/mL on average and my testosterone dropped to around 10ng/dL.

I did misspeak a bit. You're body will consider one or the other to be your "primary" hormone and will prioritize production of that and deprioritize production of the other. But all bodies do produce both through various means. And in fact estradiol is essential to male sexual development. Just non-intersex, "average" bodies are not capable of producing as much of the opposite. But if the balance of hormones changes, most people's bodies will switch, but just be unable to maintain the balance if the imbalance was caused by supplementation.

There is not a hard male/female separation in any species with genders and never has been. Hormones, genetics, hormone intolerance, and many, many other factors play into what genitals we get at birth and what hormones we make and his efficiently we use them. The x/y chromosomes have a little to do with initial selection of "primary" hormone and thus genital creation in the womb, but if the body can't uptake testosterone effectively, then having a Y chromosome will not produce male genitals and the body will default to a more female configuration and produce estrogen primarily. It's one reason the "biological sex" fanatics don't actually want people to get their chromosomes tested. It would destroy their narrative to find out just his common it is for AFAB people to have Y chromosomes, vice versa, or totally different configurations outside of people traditionally classified as intersex.

My point on taking anti-androgens before knowing if you need them is because these are uptake inhibitors and your body us still producing the hormone, but you aren't using it, do your body produces more, etc. This means, until your testicles are removed, it's often too late to switch to estrogen-only if you start with anti-androgens. But it's still not understood how common it is to need them or not, and drug companies refuse to test any hormone therapy for trans people, which is why it's always "off-label" use, so studies rely primarily on existing data and volunteers and takes decades to compile.

Your mileage may vary, but in my personal experience, estrogen gave me better mental clarity, more energy, and lifted depression and anxiety to an extent I didn't realize I had been suffering with my whole life (or more accurately since the start of puberty); that was happening within the first few months with depression lifting the fastest and anxiety lifting much later ... so based on my experience and the research that has confirmed the immense clinical benefits of medical transition, I highly recommended anyone who thinks they might be a trans woman to try injecting estrogen and seeing if it helps them as much as it helped me.

Transitioning is rough and stressful, and hormone fluctuations and figuring out the right dose is part of that stress, but overall transitioning made me a healthier, more balanced, and more productive person ... I'm not sure those changes will happen within two weeks, especially not with oral estrogen.

I don't know that your experiences with oral estrogen will be, as I mentioned they don't result in consistently elevated or stable estrogen blood levels, and I have never personally taken oral estrogen to compare.

Girls I know IRL who take oral estrogen have a variety of experiences, but anecdotally most of them have slower feminization and worse mood than girls I know who inject or use patches. I know one girl who does sublingual and had decent feminization. All of this is anecdotal and not generalizable, but what we know about oral estrogen was enough for me to avoid it, though I obviously would take it if there were no alternative. Taking 3 - 5 doses evenly spread out through the day might help achieve somewhat more consistent levels, but this is logistically challenging and needless when there are other options.

It should be mentioned I overcame severe needle phobia to inject estrogen, that's how significantly better that route of administration is. Also, injecting with very small and short needles (think insulin needles) into fat was the only way it was feasible for me, I am not sure I would have been able to inject IM with a longer or thicker needle.

To be honest, something about trying to take HRT for just a day, or just two weeks feels off to me - it takes time for the body and brain to adjust from testosterone dominance to estrogen dominance. You can't really squeeze that into tight timelines. Even after 3 months major changes are happening and I saw significant mood improvements at 4 - 6 months that weren't present before then (namely a dramatic reduction in intrusive generalized anxiety).

It's fine to try HRT on a trial basis, but I would just take it for 2 - 3 months and see how you feel. If it's working well for you, just continue; otherwise, that's when you would want to stop to avoid permanent breast growth that won't go away.

Trying to glean something out of a single day of HRT, or squeezing it into a two week period (which plausibly might give you some sense of whether it's right for you) just feels a bit misguided ... It takes a while to figure out a dose that works; to be honest I never figured the perfect dose, my biochemical dysphoria didn't go away until I was post-op a whole year later.

My advice is to start HRT and take it as long as you can up to the point of permanent changes, then make a judgement call on whether to continue or revert back. Usually it's clear for most people whether they want to continue early on, within a week or two.

This is made more complicated by the fact that spironolactone can cause depression and can be a bad time, so opting for anti-androgens and oral estrogen makes it less likely you will feel great. Others have a great time on oral estrogen and spiro (thinking of Mia Violet in particular), though that is unusual. Still, maybe you will get the information you need anyway. (Though, being real - cis men wouldn't usually consider taking estrogen voluntarily, which is probably part of why regret rates are so low - cis people just don't tend to think transitioning seems like a good idea. Estrogen only made clear that I liked being on estrogen, it didn't cure my denial or imposter syndrome.)

it's smart to worry about infertility and to freeze sperm - I agree with panathea, get on that quick!

however, you should know not only is it not 100% you will be infertile while on estrogen, there's a good chance you will regain fertility if you pause HRT:

https://pmc.ncbi.nlm.nih.gov/articles/PMC9873819/

There is a common untested assumption that this inhibition is permanent, resulting in infertility. In this longitudinal study, we report the recovery of viable spermatozoa in nine trans women who stopped GAHT for reproductive purposes. Our preliminary findings suggest that the negative impact of GAHT on spermatogenesis can be reversed, casting doubt on previous claims that GAHT in trans women inevitably leads to permanent infertility.

sample sizes are small and we can't generalize from such a small group - but it at least falsifies the common belief that HRT will make you permanently infertile, it seems like the opposite is true - that fertility is regained in the majority of observed trans women when they pause HRT.

Yes, get on that!