7dpo possible implantation bleeding?

My cycles are usually around 31 days, my partner and I BD on the 2nd and 3rd and I think I ovulated on the 3rd... I had very light brown spotting only when I wiped last night and this morning... Whats the likelihood this could be implantation bleeding as im not due on until 16th/17th. Ive had no other symptoms other than a mildly dogdy belly? Could this all be stress related as my daughter is having a regression? How soon after implantation bleeding did people get BFP?