technically, if your AF is due on 14dpo and you start spotting on 14dpo... even IF you were starting to implant that late, the pregnancy wouldnt stick.

That said, its much more likely that AF is showing.

 

I had spotting at 14 DPO, thought it was AF starting. Next day, nothing--so I took a test and I was PG! i think my hormone levels weren't quite high enough to completely suppress my period. It wasn't implantation spotting, but I was pregnant.

 

I had spotting at 12 and 13 dpo (it was brown though) but then AF never showed. I tested on 15 dpo and got my positive. I'm not sure that implantation spotting always appears on the exact day of implantation either. I think that you can spot a little bit because the egg is getting "snuggled" in there.