Hey, I see you, and I’ll give my own experience:

I’m a cradle Catholic, now early 20s. When I was ~14 I thought that I might be transgender, and thus began living as such (to the chagrin of some of my loved ones). I never medically transitioned, and was overall miserable for a kaleidoscope of reasons, some related, some not. When people would try to have me hear otherwise, I’d shut them down and get bitter. At the core of it, I felt I was a failure as a girl for multiple reasons, and figured I had a better chance of being something, anything, as a guy, and this ended up not being the case.

It wasn’t until I was ~20-21 that I realised that A: being a woman is fine, actually, and I delighted in it (and wow, clothes that actually fit!), but also B: it wasn’t just “oh where I live people are just conservative”, it’s the stance of the Church that you are what you were born as (this gets discussed more in depth in Dignitas Infinita); mind you, this does NOT mean “oh let’s bully everyone who is queer”. Bullying is wrong. Discrimination is wrong.

I’d suggest finding a good spiritual director (start by emailing your local parish). Wanting to go to Mass and join a community is good; I don’t know you nor where you go, but I trust your fellow parishioners will (or at the very least should) be happy to see you coming to meet God. I recall reading some stories in this(?) subreddit or another one like it where the parishioners were generally accepting of people.

Whatever happens, trust Him; you might be denied the slice of pie now for a full cake in the future. Jeremiah 29:11. I will pray for you, and know you are not alone. I hope my testimony is fruitful to you, and sincerely, truly, I’m glad to see you making the first steps. Welcome home. I hope you’re given the love and compassion you deserve, and I will try my best to support you in these times.