TTC, Missed Periods, Negative HPT and Blood Tests

I'm very confused. I'm 19 years old. I have PCOS. I got off birth control in August 2009 and since then my periods have been on time perfectly. My last period was March 15, 2010. It's now been 3 months, 1 week and 2 days since my last period and I'm still not bleeding. I've had sex a lot between the time of my last period and now but all of the pregnancy tests that I've taken have said negative. I took one 2 days after my first missed period and then 2 weeks after that. Then one on May 7th and then one on May 14th and all of them were negative. I also took a blood test on May 21st and that came back negative. My period was due again on June 7th and I spotted a little on June 7th and 8th but then it stopped. My period is due again on July 5th and if it doesn't come, that will be the fourth missed period. I've never missed a period in my life, and I've had my period since I was 11. The latest my period's ever been was about 1-2 weeks and now its about to be 10 weeks since my period was due. Right before my April period was due two months ago, I had cramps [around my lower abdomen/uterus and my sides] which felt like my period was going to come but it never did. Then it went away. But about a week before my May period was due the cramps came back and I mostly got them when I laid down on my stomach and when I sat down. That stopped in the beginning of June. I feel a lot more tired then usual and my friends tell me that my waist area have gotten wider. I feel naseous at times and I was REALLY congested the past couple of weeks [went away now]. And I know it wasn't allergies or cold because I wasn't sneezing or coughing. And my lower back has been KILLING me, especially when I start walking. The tiredness and nausea and back pains pretty much went away around the same time the cramps went away. But I don't know what to do because the tests still say negative. What should I do? Is there a possibility that I may still be pregnant? Or can it be something a lot more serious?

[Freds_Baby]

Why don't you go to the doctor and get a blood test done. If it is still negative maybe they can give you something to get your period started again.

[BabyKat2009]

Well, you would have normal periods on the pill. It regulates you. PCOS can cause you not to have a period.

Go see an OB. Have another blood test, if still neg ask for an ultrasound to ease your mind.