Not Ovulating?

I have a bit of an irrational fear that I will never be able to have children. I'm 23 and it seems like everyone around me is pregnant or has babies. I stopped taking birth control in September and while I was on vacation that month I noticed distinct ovulation symptoms. I even had cramping on one side so bad that I knew the exact moment I ovulated. After I got home from vacation, I have yet to notice those same symptoms and my cycle has become very irregular. I don't think I am ovulating considering it was so noticeable before. Has anyone ever had a similar experience? And is there anything I can do to regulate my cycle to ensure ovulation?