I have irregular periods, 8/14 - 8/18, 9/11 - 9/13, 10/4 - 10/8, 10/28 - 10/31,. I have frequent urination, lower back pain, tender breasts and I have been having very regular unprotected sex with my boyfriend. I thought I was pregnant but my period came on Sunday and left yesterday. Could I still be pregnant?