Hi
Welcome to the forum!
Apart from the hormone replacement, the cause for low testosterone should be found out like testicular damage by inflammation or cancer, pituitary problems or genetic. Injections are generally taken every 7-22 days depending on the level. With a very low level you may need to take every 7-15 days but this has to be determined by an urologist.
Hope this helps. Please let me know if there is any thing else and do keep me posted. Take care!
A urologist or your doctor should be able to tell you how often to inject.
I have been told to use 2CC every month and I do my own injection. Since I live 35 km from the nearest town, doing it myself was a good option.
Good luck,
Ron