My last period was June 28 it last about 5 days. My period was supposed to return the end of July but I started bleeding August 1st. I had unprotected sex on July 18, and 19.. Could I be pregnant.

If you got your period, most likely you are not pregnant.

Having unprotected sex on July 18 or 19 would in fact be the time frame you would have been fertile according to the cycle you have relayed. Are you bleeding as in spotting? If you are pregnant and spotting this early, you would possibly be miscarrying.