Building natural muscle mass is not easy, for most of us it takes years of doing things correctly to make good progress. Drugs (legal, illegal, or 'natural') will of course shorten that time line, but that's a decision you'll have to make for yourself. But let's be real for a moment, the new HRT trend has just become a quick-fix for guys looking for that shortcut. The fact that so many supposedly 'natural' guys are on HRT or pro-hormones has set an unnatural standard in the muscle building industry. But I'll hop off my soap box because it really is YOUR decision.
By constantly losing and gaining weight, or trying to stay lean year-round, I'm sure you've sabotaged your own natural potential for muscle growth. I don't buy the 'low test level' argument, after all I see girls with crap test levels that are able to gain muscle mass. I'd invite you to spend the next few years doing things correctly, the way it's explained here by BtB and the other contributors, then see if you don't start gaining and feeling better. 5 months of training, and three of those on a big weight loss regime is not something to judge your potential on.
I know I won't make friends with that, but I wanted to at least share my views. I feel better now, carry on. . .