I just came off of the pill at the end of my last cycle and think I ovulated two weeks ago because I had weird cramps on my left side. Then my libido was through the roof. I heard that happens often. I took a pregnancy test and it was negative a few days ago. Then yesterday I thought I started my period but it was just a tiny bit of pink spotting. I read that it is either implantation bleeding or a side effect of stopping birth control. Even if I am pregnant a test wouldn't catch the hcg this early, right?

My period is due Sunday but my best friend's bachelorette party is Friday night. And I don't want to steal her attention. How do I get away with not drinking just in case?