With that casette ratio buying a cmpact will be pointless you might as well walk then...isnt the aim to get faster? When I started cycling I had compact and a 11/25, once I made it to elites my compact had to quickly, I was unable to keep up on quick accelerations as their 39/53 handed out more power on the flats than a compact. Made the move over to compact and kept my 11/25 and I felt so much better and faster. Some training advice for you, I used to be coached by science to sport so a combination of recovery and intervals rides a week is good. Tuesday zone 2 light gears cadence 90+; Wednesday Intervals start with 30min warmup 1min sprint and 1 min rest, do about 10 of them and coldown 30min cadence 90, thursday recovery zone 2 high cadence 90+... This way you will burn fat and gain speed on bike. I used to weigh 120kg, race weight was 76kg, I managed to mantain my weight after I stopped racing at 80kg by proper diet and still riding 4 times a week.