One of my favorite movies reminds me a lot of you. It's called Zootopia. If you've never seen it, it's about a rabbit who wants to become a police officer and "make the world a better place". Her whole life everyone tells her she can't, including parents and mentors, and even when she does achieve it she's told to quit. It's very hard for her to even get there because, well, a bunny isn't physically the ideal cop... So she works that much harder where she is flawed and makes it happen. When she's told she should quit and isn't given a fair chance to prove herself she pushes anyways and by the end of the movie (of course, because it's a movie) she wins and makes the world a better place.

Of course, I know it's just a movie and real life doesn't really work that way, but in some cases it can or at least similarly. I'd like to think you're such a case where it's gonna be very difficult and there's a lot going against you, but you can still do it if you stay determined.