Could I be pregnant?

So my last day of my period was April 22, 2016. I had unprotected sex around the end of April and throughly the beginning of May as I May 3rd through that weekend.  Around May 15th I had small bleeding my period is suppose to between the 19th and 23th. I took a dollar tree pregnancy test around the 19th and it was negative  I think I had another spotting it's the 22nd. Is this implantation bleeding am I pregnant?