help please

Avery • Wife of Chase Farr🔐💖 Marines❤️
I've missed my period by 12 days. I took a pregnancy test this morning and it was negative and I take 3000 milligrams of vitiman c a day for about a week now to have a type of birth control. Please can someone tell me why I'm not getting a period? The last time I had unprotected sex was over a month ago.