WTFFF

so my period was due on friday, i was cramping like i was about to start but i never did. well friday night i ended up getting fucked up and was throwing up half of the night, im only saying this incase me getting sick or drinking could have something to do with it. well saturday my period still never came. yesterday it finally came but barely at all, it was VERY light and just looked like old blood. this morning i woke up and it was just gone completely. i have been on the pill for almost two years now and ever since my period has never been late or irregular so i am really thrown off. i dont think i could be pregnant bc although my boyfriend dosent use condoms i take the pill religiously and he never cums in me. what could cause this?