Mood swings

Ive been having issues where one minute im happy the next sad. One min i wanna be wirh my bf the next i dont . One minute i wanna talk to people the next i want to be left alone. I usally only get this way when im on my period but im not. My mom thinks im bipolar like my dad but i dont think its that server my friend thinks im pregnant but ion think a pregnancy canbe based off of mood swings... Anybody have this issue, that can give me some ideas of what my problem is majority of the time my bf is the cause of the though