“I do it because it’s what I do, it’s what I was commanded to do, and that’s it. Reward?”
I’m not sure that this is a negative. If you look at it from a different perspective, you are doing it l’shem shamayim- because you are commanded, not to get a schar. that seems to me to be a very high level.
If you are feeling that you are just doing things by rote, then that is something else. But this does not sound like a spiritual issue, but rather an emotional one. It is the depression talking. If you couldn’t daven properly because you were terribly sick, lying in bed, would you think that you are a horrible person because you didn’t daven? So, too if depression is affecting your approach to mitzvos, it does not mean you are a rasha. I hope you can deal with the depression and see how valuable your mitzvos are.