Hello I'm 16 I Have Irregular Periods , I Am

Hello I'm 16 I have irregular periods , I am sexually active , I had sex the next day I got off my period and didn't use protection. I had my last period jun 7 -13 & had sex for 10 says straight with out protection . I feel like throwing up, tired,light headed and some how I feel movement in my stomach but it is not hard . it happens every day . I took a pregnancy test today 08/23/15 and it came out negative can I be pregnant