I am 15 and I think I am having a pregnancy scare or that I could be pregnant. My last cycle was on July 28,2010 and I had sex on August 11, 2010, which was around the time that I was suppose to be ovulating. I did not use protection. In Sept. I started getting cramps thinking that my period was coming but it was a no show. I also had a lot of gas but I don't have a lot of gas anymore. Sometimes I get like this pain across my stomach but I don't know if that has anything to do with it. I get nauseated when I get out of bed in the morning sometimes and after I eat. Also I get bloated after I eat and it makes me look like I am 3 or 4 months. I feel very tired even when I have a good night of sleep or sometimes I just can't sleep at all. I took 3 home test and they all came out negative so I'm not sure now. I am feeling like I am but I don't know. Should I get a blood test??

It can be many things, but you need to check with your doctor.

It could be that you were just stressed, but you should check with your doctor.
If you are going to be sexually active, getting on birth control and having the guy use a condom will alleviate some of that worry.
15 is too young to be worried about such things and you worry when you are irresponsible.

Stress could be playing a role in causing these symptoms. Try to stay calm and just relax. If you continue to feel these pains, consult your doctor immediately. I understand that at such a young age you wouldn't want to tell your parents and consult a doctor. Try to take on more pregnancy test in a couple of days as soon as you wake up because the test are more likely to be accurate if you take the test first thing in the morning. Again if these symptoms do not go away soon, consult your doctor immediately.