No sex in 4 months, on time for period til this month?

i haven't had sex in 4 months and i've been having normal periods until this month, i was almost 3 weeks late.. finally started ovulating and in 2 days its almost over....pregnancy test almost every week and all have been negative, is there any chance i could be pregnant and not know it? i have a child already... i'm very paranoid. PLEASE NO BULLCRAP RESPONSES!!!!!!!