Dry Bones Valley,
I reccomend the book "Centered Riding" by Sally Swift. She had physical problems that made it difficult to ride. The concept and classes are structured around feeling the horse, and your body in space - connecting with the horse. Second edition is better.
I have taken two workshops through some top Centered Riding instructors, and have learned a great deal from them.
DBV, if you can get on the lunge line, do it! It will really help. Also, remember that you CAN ride the bolts, you've done it before. Usually the horse isn't actually going that much faster than normal, it's just the surprise factor.
Are you thinking of a handicap ramp as a sign of inadequacy? It's not. Riding is about being on the back of the horse, not how you get there. Plus, the less stress you put on the horse's back when mounting, the better it is for the horse!
You sound very determined, keep up the good work!