Low Test is common in overweight men. Problem is, the aromatase enzyme (which converts Test to Estrogen) lives in fat cells. So, more fat = more estrogen. Which is what's happening to you now. High estrogen then suppresses the hormonal axis responsible for producing test.. It says "Too much estrogen! So, gotta make less test, so there's less conversion to estrogen".
Two routes of solving it: Lose weight. Doesn't matter what the problem is; too much food, too little activity, thyroid imbalance etc. Get it solved for your own good, Man.
To just raise test: Start using an Aromatase inhibitor (Estrogen conversion inhibitor). Most of the the studies done on Estrogen Inhibitors in men, like Letro/Arimidex/Aromasin were done in obese populations. So there's data showing improved Test levels using just an AI.
Adding just TRT Test to you system now would have low impact and create a ton of estrogen conversion.
But low test is just one and the least of the problems here. I'd be getting a Thyroid panel done and sticking to better meal plan. Good luck!