major worried!!

I cant remember when my last period was and of course like a moron i have unprotected sex i had a baby 4 months and 2 weeks ago and habemt had my period yet! SUPER FREAKING WORRIED! I usually get my period arpund the time my work friend does, shes having hers and mine STILL HASNT CAME!! I SO DINT WANT ANOTHER BABY SO SOON!!! I took a test last week, it said negative but im so fucking worried and my idiot boyfriend doesnt care either way and ive told him multiply time i want to start using condoms but he doesnt listen HELP!!