What does the pill do to your period?

Wondering what other people's experience was when they started taking the pill - did you miss periods, get spotting, etc.?

I started taking the pill (junel 21 days) and just finished my first 21 pills. I'm spotting a little bit these past few days but I'm not sure if that's from sex (just started having sex recently) or my period starting? I've heard the pill can do funky things to your period. I just want to have a solid period so I can rest assured I've made it through my first sexually active month without getting pregnant!