Implantation Bleeding on 1st day of AF

I took a pregnancy test yesterday and it came out as a grey line (it was a ept early results test that are supposed to be blue answers + or -) so I just assumed that was a no. my last AF visit was July 7 and my cycles are anywhere from 24 days to 27 days well me and the fiance DTD every other day for the past few weeks trying to conceive and I have been having heartburn a lot which I had never had before insomnia at night then fatigue in the day sore breasts and cramps for about 2 weeks or so now but today was my expected visit from AF and its not as heavy as it usually is on the first day just some pink blood every so often. is it possible that its implantation bleeding not AF?