Hi, I'm 29 years old man. I have the testosteron level like you (first time 359, second time 426)
Conclusion : You have approximately 55% of testosterone amount in comparison to 21yrs men average.
I ask my doctor how I can increase a level of my testosterone. Hi said that products (sport suplements) with 'Tribulus terrestris' can do that. 'Tribulus terrestris' leads to rise of natural (endogenous) production of the testosterone in your body.
I tried some suplements with 'Tribulus terrestris' and few first days was interesting, but after approx. a week I didn't feel any effect - Maybe becouse I bite that pills. I heard somewhere on teh TV that if the suplements/pills are covered with hard layer of something then this pills should be absorbed in your bowels - If you bite this pills then acids in the stomach destroy the ingredients of the pill.
Sorry for my worse english.