I want #4.

How do I get started. It seems like I can't get pregnant?!!?!??! (I know alot of people probably feel this way.) Anyways, I have 3 kids, they're wonderful, wouldn't trade them for anything. Well their father and I broke up, and I got married to a different guy(he has no kids). He is Wanting a baby, and I have baby fever so bad and want another. Seems like I can't get pregnant. Since I came off my birth control last August my periods have been so irregular. Right now I'm about 3 weeks late(MAYBE), I keep taking test, keep popping up negative. Ughhhhhh.