Is eating a lot of meat bad?

My cousin who is a personal trainer says if I want to get my muscles better and repaired faster, and all that good stuff then I need to have more protein.

So I meat for almost all of my meals with some bread and stuff, but my mother says that Dr.OZ is talking about how they inject a lot of hormones in the meat and that the more protein you have the higher chance you have for cancer. And that it’s bad to have too much hormones.

Is my mom worrying too much? How correct is she?