Because this is a weightlifting question with nothing to do with PUA subject matter, it might be better to post on a weightlifting forum. I'm not trying to be rude, rather, you will probably get better information from people who are primarily weightlifters. For example, they might tell you to:
- 1) Add carbs to your diet. It takes more than just protein to gain muscle, and it sure as hell is going to take more than a cup of SPAM. That will be an improvement over your current diet, but it will not be enough.
2) Change your routine. The human body adjusts itself to diets and weightlifting routines, so that the exact same effort that worked so well six months ago suddenly stops showing the same results. It's called a plateau.
3) The manner in which you lift weights may also need to change, like to a higher weight/lower rep routine.
I am both a PUA-in training and a longtime weightlifter. My PUA questions go here and my weightlifting questions go on the weightlifting forums.
Would you expect to get a good answer from a PUA question on a weightlifting forum? Most likely, no, they won't know what you are talking about. Then why try to find a good answer to a strictly weightlifting question in a PUA forum?