Hard time

I don't know what we are doing wrong. I'm 19 and he is 24. We are on month 11 of trying. My periods have been regular and then just this past month is was messed up. Came on cycle day 20 instead of 34 (like usual) and lasted like 10 days and then came again on cycle day 20 of a new cycle. I actually hate this. It has to be me. He's gotten his ex girlfriend pregnant before so clearly he's not the issue.