I need help, I missed my period.?!

I need help, I missed my period.?

Here are the details:
I'm 21 years old, normally I'm on a regular cycle, 28-30 days. I am NOT sexually active, I haven't been for a couple years now, so pregnancy is not an option. I've never been on birth control, and I'm not taking any medications.

Here's my question. Several months ago (Nov. 2006) I had my period, but missed it until February of 07. I read a few articles, and they said it could be a sign of stress, which was more than likely the cause. I got my period back on schedule for the next couple months when my stress died out. I'm somewhat worried now, because my last period was in April (2 months ago) and I have zero stress in my life right now. I also read weight gain/loss could cause this, but I haven't done either. I'm completely lost right now!

I'm just wondering if anyone out there has any clue as to what could cause this?

(I'd like as much info before seeing my doctor. Thanks!)

Sometimes it just happens. Have your doc check your hormone levels, they can tell if you have a hormone imbalance or what may be the cause. Enjoy it, I know it is hard when you want to know what is going on. Your doc may put you on birth control to help straighten things out, he did with me. Good Luck!