It is possible to learn to shoot pretty well with a disability if you can be consistent, even if you're consistently doing the “wrong” thing by contemporary standards. Maybe even better than pretty well. There were some brothers early in the last century, Walt and Ken Welhelm, who were champion trick bow shooters. One of them, I think it was Walt, had a shoulder injury that prevented him from raising the bow into a normal shooting position, so he learned to anchor the bow on his waist somewhere, and with that anchor and a lot of practice, he was able to shoot small objects out of the air. Just shoot as much as you can and be consistent in what you do. Either through your own experience or by watching videos, ideas will occur to you from time to time on ways to improve your shooting. Try them out, and if you can manage them with your disability and they seem to help, incorporate them into a new consistency. Just make changes slowly: evolution, not revolution, is what you're after.