Normal testosterone levels can vary from day to day, and at different times of the day. Often, if a man is close to the cutoffs for low T, doctors will test twice before deciding on treatment.
Morning is often the best time to test, as well.
Before you decide on anything, if you haven't had another test to confirm these results, given how close you are to normal, I might get a second test done. Going for injections every 4 days seems like a big jump if the confirmation hasn't been made.
Heavy alcohol use - more than 15 drinks a week - can affect testosterone levels.
https://www.healthline.com/health/how-alcohol-affects-testosterone
If you drink more than 15 drinks a week, I'd certainly try lifestyle changes before doing injections or trying supplements. I'm with your wife on the supplements - most of them haven't been studied that well.
Basically - try limiting the alcohol, eat well, exercise, get enough sleep, etc. Tell your doctor you'll try that for 3 months and test again.
Also, some medications can lower testosterone - https://www.issm.info/sexual-health-qa/can-prescription-medications-affect-testosterone-levels/ If you are on any of these, talk to your doctor.