I had nausea a week before my period and lower back pain. I have been constipated for a week. I came on my period but only for 3days. The first day was heavy the second day and today are very light. Usually I am on for 5days or 6. It was also like a light red. Not bright red like a medium dark. No blood clots as usual either. I had unprotected sex for three days and their were three days before my ovulation. Could I be pregnant and if so when should I take a pregancy test. Also, off and on I'll get pains in my breast.

If you were pregnant you would not have an actual period. It was likely just an irregular period. Wait until your next period is due... if it comes you have your answer... you aren't. If it doesn't wait another two weeks then take a test.

Taking one too soon will likely get you a negative so you are better off waiting.

But honestly.. I don't think you are.