Few things.
1. You are a junior, as long as you are "fit" don't worry about loosing weight. You're gonna keep on growing, you'll have massive strength gains for the work you put in. Shaving weight may hurt your ability to recover from the workouts. Leave the weight obsession up to 25 y/o+ idiots.
2. Buy the cheap ass wheels. You are a junior in cat 4, crashes happen. Plus I can't think of one instance that a cat 4 won or lost a race due to advanced equipment. Most 4s are leaning how to sprint, position, and pace in breakaways. The advantage that aero wheels add in is so small compared to a good grasp of those skills.

But I will agree that carbon rims are sexy. Get some 50mm for the aero advantage (1375 grams is light). Good for crits, RRs (as long as it isn't super windy), and TTs.