My body is going crazy!

I'm tired of my period starting too early or not starting at all or starting late. I want to get pregnant. But it's so hard to get pregnant when I don't know when I'm going to ovulate or even if I'll ovulate. I'm so disappointed with how I feel like my body is working against me or betraying me in a way. I'm doing everything I can within reason to be healthy and a good weight. I want to be jealous or envious of women who don't take care of themselves as well as I do, but I can't even do that. Some days I just want to curl into a ball and cry my eyes out. It's so disheartening and I don't know if I should even look forward to trying anymore.