wth is wrong with me?!! Spotting !!!

I got my period on April 22nd ended it on 27th. (Been active with my hubby since we are ttc). And then I started to slightly spot. It's now May and I'm still slightly spotting not all day, or everyday. When I wipe there is a pinkish color, I've been using a panty liner and I've noticed spotting. I've taken 3 PT and they are from $1 tree the little white and purple ones, and they are all Neg. technically it's only 3 weeks, but can I be pregnant? Can a test still show neg. after three weeks? I have a Dr apt on 17th to discuss all of this. Also today I had a very bad migraine it was horrible. I ended up leaving work. Now I'm in bed with a feeling of nausea. Has anyone else ever had this issue and was pregnant?