I'm 23 years old, sexually active,have an inconsistent period for 2 consecutive months - July and August (last month, 8 days late, and it's unusual than the regular period I had since my period begun), this month I'm already 3 days late. I've tried home pregnancy test, and all came out negative, but having some pregnancy symptoms for the past 2 months (headache,swollen breast, bloated, nausea every afternoon, more vaginal discharge than the usual), I'm not using any birth control.