Late implantation???

K❤️🌈🙏👶 • We welcomed our beautiful daughter Ada-Grace on the 07/02/2020 @ 17:27pm 2 weeks early ❤️ Our rainbow baby 🌈👶💜

Hey lm 4 days late as of today and 1 im never late its like clockwork down to the time and 2 my af starts off brownish and alot more. Is it possible i ovulated late and implantation is only talking place? Did a PT yesterday and got negative.. So confused.