Light brown CM after light BFP on FRER 13dpo

Vanessa • Married for 7 years & TTC for 6 years. IUI 1-5 BFN. We`re now happy adoptive parents! 9-2019 = IVF to make our little one a big sister! ^_^
Has anyone else has light brown cm 13dpo and still ended up pregnant?
I'm feeling so down right now I can't help but feel like that's a sign that AF is on its way tomorrow. 😰