One of the many mistakes I made learning to paceline was to try to pull too long at the front and then be so whipped I couldn't catch on at the back. Stay in the rotation just stay at the front a shorter time. It really helped me to ride with a buddy who would push me on the days I would otherwise have ridden solo. i've been really fortunate to have two friends who are experienced riders to teach me and force me out of my comfort zone regularly. I am older and bigger than you but my abilities have really improved in the last year with the help of my friends. I am routinely riding with people I've never been able to ride with before