[gwys]

The number one thing you need to do is logging. Without measurements it very hard to know what's going on. You might very well go to the doctor and check blood levels, intolerance and the like. But that is mostly a one time thing. You need to be constantly logging all your workouts and diet and then test yourself every 1-6 months (different for different tests). You'll at least want body measurements, bmi (be accurate, but not to often), aerobic performance, strength performance.

Get some screening, then go to someone who knows their thing, get homework, do homework for a couple of months, come back and you'll be in a very good position for improvement or at least arguing your case.