Confused...

So.. My bf and I had sex the day after my period ended. That was 12 days ago. This week, i have been nauseated, having migraines, hot flashes, and have been using the bathroom slightly more than usual.. Is it even possible to get pregnant the day after your period? Or am i just overreacting? Have two angels, and trying to conceive my first rainbow. Been trying since March 2014...