Hello benajah,
First, IMHO, it is great and tremendously courageous of you to get back into racing. I really can't offer any advice on training better, though I wish I could.
However, I want to relate a story about racing in the 1980s as a Cat. 3. There was a guy from San Diego who raced with one leg. I believe his amputation was just above his knee and he raced with a prosthetic leg. He raced most of the SoCal crits at the time as a Cat. 3 and most of the time he was able to stay in the field. I'd be next to him in the pack and I remember thinking that if this guy could do that well with one leg that I had little to complain or make excuses about with my racing.
I just wanted to let you know that it can be done. I am sure that there are qualified coaches that can help you achieve your goals. Wishing you all the best.