Congrats on getting into the sport and finding yourself getting stronger and faster. It is a great feeling and will only get better. And you should feel proud of yourself since building strength takes commitment.
In my 30s, I moved from a heavy steal frame to a lightweight steel frame, and it helped with quick accelerations, getting going from complete stops, and make hill climbing easier. However when cruising at a constant speed, say 18-19 it really didn’t make much difference.
As I have aged, I have found aero wheels and low rolling resistance tires to be a help in maintaining the same speeds on the flats. If you are looking for new rims too, 45mms seems to be the sweet spot.
Keep up the good work!