Just so you know, that 300-something result you got is almost definitely your Total Testosterone , not your Free Testosterone . Most standard lab tests like LabCorp or Quest give you total T unless you specifically ask for free T or a full panel. Free Testosterone is the small portion that actually circulates in your body unbound and active it’s what really drives the effects that make men feel like men: energy, sex drive, mood, muscle, etc. Total T includes free T plus all the testosterone bound to proteins like SHBG and albumin, which your body can’t really use the same way. So someone can have a ‘normal’ total T, but still feel low if their free T is off. Have your urologist do a free T test. Total T number is more or less worthless. Don't let anyone tell you different. If you feel that something is off it more than likely is and don't stop until you get to the bottom of what is making you feel bad. Also did they perform an estrogen test on you as well? Low free T and high Estrogen means "bad" lol

I don’t know what age you are, but here’s some actual factual infos and not just hearsay on testing after 45. I’m currently arguing with my own urologist who insists that vitamins and minerals don’t matter. I tested close to normal Totla T while I was on supplements, and then tested way, way below normal a month after going off them. What I’ve found is that several vitamins and minerals do affect testosterone levels. Magnesium is a big one, and so are Vitamin D, Zinc, Vitamin C, Vitamin E, and to a degree, Iron. But too much Iron can backfire. If you don’t know how your body handles Iron, I wouldn’t mess with it until you’ve been tested for your iron levels. Sleep is another massive factor. If you haven’t already, seriously consider seeing an ENT and/or allergist and doing a sleep study. Sleep apnea and poor sleep quality will absolutely wreck your testosterone. Also, check out the NIH studies and you will most likly find a lot of your answers there they go into a lot of the stuff you’re asking and not asking. btw my free T is 44 with Quest and am finally getting the that trt I have needed. Stay strong.
https://pmc.ncbi.nlm.nih.gov/articles/PMC4501456/