I am 32 years old, I have always has a normal period up until March 2012. Since March 4, 2012, I haven't had a period, but on April 19, I started spotting and passing small blood clots (smaller than a quarter). I have taken at least 3 home pregnancy test with negative results. The spotting or clotting causes no pain at all. Would could be going on with me?

Any number of things could be going on. It would be impossible to tell you for sure. That's what your doctor is for.