Mikki,
I had really irregular periods too when I was a teenager. I started taking birth control to help make my cycle more regular. It would probably be too early to be having any symptoms yet (because it could still be before implantation even). The symptoms are probably from stress. If it has only been about 4-6 days since you had sex it would be too early to take a test and be able to detect a pregnancy. Normally I would tell you to wait to take a test until you miss your period, but if your cycles are very irregular this might not be the best advice. I know waiting without knowing is stressful, but I would wait about two or three weeks and take a pregnancyh test. Good luck.
Kate