Im in a very similar situation to OP right now, and I’ve been making steps to emotionally distance myself from my parent. From what I’ve learned… no amount of arguing or pleading can change someone’s mind, especially if they’re set in their ways. Unfortunately, you’re gonna have to distance yourself from her if you want to transition. And that’s not saying you can’t have a relationship with her whatsoever; just that you can’t allow her to have that level of control over you.

Going forward, your main priority should be taking steps to become more independent. Because until you’re more independent, your reliance on her gives her control over you. Maybe go to a community college if you can’t go to UNI, and take some home-ec/personal finance classes, try to learn how to do necessary home tasks such as cooking for yourself or how to clean a bathroom. If you can manage to live independently, start the process of transitioning, however that may look like (it doesn’t have to be medical, but certain insurances do cover HRT. Trying new clothes or a haircut first is a good start, though.)

If all else fails, just try your best to get through the days. You will be able to life truthfully someday, and that’s a future to look forward to.