@ goober and Avles
Goober is right in fact that the OP getting back to 4.5 is not all that impressive. Players who have built up the muscle memory as a junior will always have a higher ceiling than the folks who came to the game late.
However, what you can be impressed with is making the effort after so long away from the game. I will tell you that once I stop playing tennis it will be golf full time, and you will never see another post from me again.
FWIW ... I am a 43 year old that did not start until my 30's and just this past year was bumped to 4.5 ... so it can be done. However, my strokes will always be unorthodox compared to someone that learned proper technique when they were 12. I will never be able to develop a 5.0 game with my current technique and I have neither the patience or the time to completely renovate my strokes.
"You should be playing linebacker, not singles."