E.S.
You may still be pregnany but you are not producing enough of the HGC horomone for a pregnancy test to read. My Dr once told me that does happen early on in some pregnancies and in some the woman never produces enough. It is nothing to worry about if you aren't producong enough, but you do need to see your OB. If you can't afford a Dr's bill, go to Planned Parenthood. If you aren't pregnant, they can help you in also getting onto birth control for a cheap price.