I've had irregular periods on and off my hole life. my cycles began when i was almost 13, i lost my mother when i was 14, and that started it. i began having eating issues that were assumed to be anorexia, but i just felt completely nauseous when ever i was upset, and that made my cycle worse. but mine was always stress related, the more 'even keeled' i feel, the more regular my hole body is. have you tried relaxation techniques? i have been doing yoga regularly for about ten years, and by regular I mean about once a week for at least and hour. It has help enormously!
Google 'yoga for relaxation' and see what you can find and what you feel comfortable with.
Good luck
It's very possible to get pregnant with irregular periods. (mine are and I'm 31 weeks along) it's just a bit harder because you don't know when you ovulate. Try looking into getting OPKs and charting your BBT. These will help you to have sex on your most fertile times and increase your odds of pregnancy. You could also talk to a doctor to make sure you're ovulating and that there's no underlying issues.