I haven't read all the replies but:
1. What kind of lifting program are you on? If you are not working a specific program I would recommend Wendler 531 or Starting Strength to set a base line and make sure you are training effectively
2. Like others said, low fat = bad. Fat = energy. You do want a certain amount of protein if you are strength training and carbs but add more fat from good sources like coconut oil, coconut milk, avocados, olive oil, wild salmon, grass fed beef, grass fed butter, eggs etc
3. I did some serious research on TRT a couple of years ago. It is a big commitment and expense. Most legitimate doctors wont' prescribe it and insurance won't pay for it unless you are a teen or in your 20s and have the testosterone level of a 80 year old man. I do believe that most of us in our late 30's and older can benefit from more testosterone but it's expensive without insurance. Most of the clinics are total rip offs. I found the best option would be the black/grey market. Testosterone is an anabolic steroid and unfortunately I found that it would be much more affordable going through the same sources that body builders and guys at the gym go. I don't condone that because of legalities and in the end I decided not to pursue that because of that and as you said commitment to never stopping because your body will stop producing it's own