My Boyfriend And I Are Trying To Have A Baby.

My boyfriend and I are trying to have a baby. Last month on August 3rd was the first try...a week went by and I spotted for 3 days off and on and then took a pregnancy test which was negative. We have continuously been trying. I have been having cramps and I took 2 more Pregnancy test September 9th and 10th...both negative. I usually have my cycle in the middle/ end of month so my next isn't due yet but today I had a small blood clot then a little more blood. Could I be pregnant although the dollar store test read negative? Please help I'm totally confused.