Hi I'm 17, I had my last period in the beginning of March around March 10 or so. The day after my period me and my boyfriend had sexual intercourse.. he ejeculate inside me.. it's now March 23 I'm starting to not feel like myself. I get flutters like butterflies in my lower stomach .. I'm bloated all the time... I get nausea sometimes.. I took a pregnancy test it came out negative but why do I have these symptoms.. someone please help thank you.