I Had My Last Period August 11-15 Had Unprotected Sex

I had my last period August 11-15 had unprotected sex August 22nd and was supposed to ovulate August 25 I spotted brownish colored blood on August 27,28 and 29th would this be implantation bleeding? I'm supposed to start my period again today or tomorrow have no signs of it starting usually I can tell when I going to start. I guess my question is am I pregnant if so when would I get a positive pregnancy test?