My Workout and need for Advice!

Greetings! This is my first post so bear with me as I give a little history... I am 43 and a professional musician. I swam USMS in the 80s. I was competitive all through high school (graduated in '78), I was an ocean guard for 6 years on beautiful Nantucket Island, I coached HS swimming and taught advanced lifesaving and water safety for several years. I am recovering from a 4 year illness and began swimming again in November. A year ago I could barely walk let alone swim. Now I swim 4x/wk in a 25 yd indoor pool. My top yardage to date is 4000. My current workout goes something like this... (all free) 1000 warmup (average 20 minutes) 2x500 (1 without and 1 with paddles) 5x200 "Lungbusters" (3-5-7-5) - tough cause I have asthma! 5x100 on 2 minutes 6x50 on 1 minute 200 warm down I have always tried to go from distance to sprints in all my workouts. Now the catch - I had back problems and got used to pulling my entire workouts. I am trying to break the habit. I just bought Vertex II short blade training fins as a start. I am fairly tight in my build so I have to be careful not to do any damage as I try and get my kicks back. I would appreciate feedback on my workouts as well as advice on my kick training. I am very self motivated but have as a goal to rejoin USMS in the near future. It is great to have access to this wonderful forum and I hope to see you all at meets in the future!