Chemical pregnancy?

I'm supposedly 15dpo I finally got a faint clear postive last night after so many faint faint results...I have been cramping since 7dpo. Now this is all a guess on the ovulation because glow says I'm 11 days late on my period (I'm pretty suee i ovulated later than predicted)....and the only time I could have gotten pregnant was 15 days ago but the thing is my husband and I only had unprotected sex for less than two minutes so it would have had to be pre cum. I have no idea what is going on. I have two very clear faint postives but this morning when I tested again it was still,there but fainter than yesterday....