Irregular periods

So I’ve been having irregular periods since last year. I am currently 4 months late on my period. Never have I been on birth control & I have gone to the doctor & had an ultra sound done to see how my ovaries are, & they are perfectly fine & nothing alarming. My boyfriend & I never have used protection & we aren’t try to get pregnant because we want to wait two more years at least, but last night we had sex & he did finish inside me. I don’t know how high of a chance I am at getting pregnant. Has anyone gone through this before ?