Okay, I'll try to help. I'm tired, ill and disorganized, so bear with me as I ramble.
1) You should make an appointment with a GOOD endocrinologist or urologist in your area who is up-to-date on the current research and experienced at treating hyogonadal men. If you need help finding one in your area, let me know and I'll try to find some candidates.
2) You will want to have your testosterone levels tested at least twice more before you consider starting any Rx treatments. Testosterone levels are extremely variable and easily suppressed by certain stressors; it's possible for a normal, healthy male to get sick, drink to excess, become sleep deprived, etc. and consequently test lower for testosterone than the average adult female. This is why repeat tests are crucial.
3) Yes, healthy testosterone levels are very important for bone density. Perhaps you experienced stress fractures as a result of poor bone density which in turn was caused by low testosterone levels, OR perhaps both of these things were caused by something else, OR maybe, again, your low testosterone levels are transient.
4) Yes, there are OTC products such as
http://www.nutraplanet.com/product/ergopharm/6-oxo-extreme-75-caps.htmlwhich help boost testosterone. IMHO, they'd only be useful treating hypogonadal men in borderline cases--in more severe cases, drugs like Clomid, or A-dex or TRT would be much better choices.
5) Optimally, someone your age should have testosterone levels well over 4-500.
6)If you are seriously hypogonadal, treat the condition first and worry about competing later. Yes, you may need to stop competing in drug-tested competitions. So be it. Your health is more important, and besides, you won't be competitive if you're seriously hypogonadal.
7)Why could a 20-something male be hypogonadal? All sorts of reasons--genetic, illnesses, injuries, stress, nasty environmental or industrial toxins, radiation, etc.
8)There are also OTC substances which may help re: stress fractures. I'm a huge fan of standardized extracts of Cissus Quadrangularis such as
http://www.nutraplanet.com/product/primaforce/cissus-40-ketosterones-120-caps.html