Have you spoken with disability services at these three schools yet? I suggest you do so and see what they can offer you. A friend who has a physical disability did just that and the differences and accommodations offered were very different between her top 3 choices. She chose the college that had the most support and was the most welcoming and says it was a very good decision.
I wouldn’t rule out UCLA altogether, but I agree with @Corinthian that it is a very steep and hilly campus and I would think that it would pose more of a challenge than a place like Pomona, which is pretty flat. I also agree with the posters who are saying that you will miss out if you can’t live in a dorm freshman year.