If you can’t move out for a few more years, you can try to believably-gradually seem to turn trad/conservative and end up renouncing being trans or whatever. However, if there’s a way for you to move out soon, probably it would work to just point-blank deny it each time she asks even if she doesn’t exactly believe you.

It’s good that she hasn’t seen the vial, hide it well and get a skincare bottle decoy yeah.

Hiding stuff has an increasingly higher chance of discovery over time, since you are basically rolling the dice on it each time and eventually you might get a bad roll. I wouldn’t freak out about it now, but considering all possible options of how to move out asap would likely be a top priority. Another way that would work is to find other trans people or trans-accepting friends who might be ok with you keeping your E at their place and taking your injections at their place.

I know some young adults are in v tricky dependent situations like living in the middle of nowhere, parents stopping them from getting a driver’s license, disabilities make them unable to study or work, etc. I don’t mean for what I say to be out of touch.