In addition to measuring your output / a longer extraction, you can try a longer pre-infusion, or bumping up the temperature. 190F is on the very low end of what is usually considered ideal -- you could try aiming for 195 - 205. Also, if the portafilter is not fully heated that will offset the brew temperature and cause lower extraction.
Are you using the Stilosa stock, or do you have a bottomless portafilter etc.? How long have you had it?
For me, I wouldn't have wanted to upgrade to the Elizabeth directly. After the Stilosa I moved to a Breville Bambino Plus. That solved my biggest issues with the Stilosa (lack of temperature stability and a crappy steam wand), and let me get a bottomless pf and unpressurized basket and learn how to get really good puck prep and dial in by taste. Plus the steam wand was good enough to really learn latte art.
My main reasons for the upgrade to the Elizabeth are to have more fine-grained control over temperature, pressure, etc. for better shot consistency and control when dialing in, plus an even better steam wand. But back when I had the Stilosa, personally I wouldn't have known what to do with that level of control. Obviously your experience may differ, but I wouldn't change my choice of the BBP as the second step on my espresso journey.
Bambino Plus gang ๐ช
The Go looks like a good machine. A dual boiler was important to me because I make a lot of milk drinks so being able to steam milk while the temperature stabilizes for the next shot is really nice. Other than that my requirements were temperature control and a relatively small footprint (though I have to say, upgrading from the Bambino Plus to the Elizabeth was still quite a shock as far as the size difference)
Also, a URL option would be nice. It seems Lemmy has trouble with the "moving" image format, so I ended up hosting elsewhere.
Gotcha -- yeah I can confirm the thermocoil (at least in the BBP) isn't very stable. If you don't care about simultaneous steaming & brewing, to get good stability you could go for a single boiler machine with PID like the Profitec Go, Lelit Victoria, or Ascaso Steel Uno. Note the PID is important -- it's basically a smart controller to avoid the boiler overshooting the target temperature, so you get much better consistency.