So first off I'm 25 married on because and have a 2 year old. About a week before I was supposed to start my period I had a brown discharge which has never happened to me before. It lasted about 3 days. Then nothing.. no pms(which for me is very noticeable) and no period. Its now about 3 weeks late. Ive taken 4 first response pregnancy tests all being negative. I've felt sick like I did with my first pregnancy, have had headaches, and bloating. Any idea what could be going on?

If you're having sex, then yup, you could be pregnant. Nothing is 100% fool proof. Only a blood test will know for sure. There are many other things that can make you late. Stressing about being pregnant is one of them. Sometimes when a woman gets it in her head that she might be pregnant, she even develops some of the "pregnancy" symptoms.