I have officially missed my period for one month?

I have missed my period for one month and i did bleed just a little the week after like for a second while my boyfriend was doing this with me i have taken three pregnancy tests and they all came out negative i have missed periods before and i am a dancer so i work out a lot we did have sex a month ago but he kinda went in for a little before he came he pulled out i think i have been eating a lot because i am off my medication but i dont know if i should go to the doctors? could i still be pregnant?