My situation was extremely similar, with the uni, my moms view, not being able to start hormones...I started hormones when I told my parents I was moving out. They knew my motivations, they knew it was for hormones and even called me out on it. I didn't deny it. I said yes, that was the reason, I couldn't live this way anymore and if this was the only option, I was happy to accept it.
Long story short, we came to an agreement that I could start hormones in the home because they didn't feel I was in a position to support myself financially. I ended up in a seedy basement suite for less than a month lol.
It still took like a year of hormones for my mom to stop calling me her daughter and stuff, and I had to call her out on it a number of times for her to quit it. It's only recently, after 2.5 years, that she calls me her son to other people.
I think what I am trying to say is that parents eventually get over it. Sometimes HRT is the only thing to make them see that this is what is best for you and that this thing is really happening. Could you perhaps make a contract with your mom? Tell her that this is something you need. That it has been many years and you need to address this issue. But that you want the home situation to be happy and stable, and that you are willing to do x amount of chores, keep up with your grades, basically make an agreement with her that you aren't going to let the transition "ruin" your life. That was a fear of my parents, so when I moved back home I agreed to things like doing certain chores, walking the dog, and giving them at least 3 months notice before moving out in the future.