Implantation bleeding?

Amber • Married 3/7/15. Miscarriage April 2015. Rainbow baby boy 3/5/16 💙 Baby girl 10/30/17 💗. Baby 3 due 4/12/19 💕 Completely in love with my sweet little family!
AF isn't due til 6/28. Yesterday and today I've been experiencing light brown spotting mixed with light creamy CM.  Implantation bleeding?  Or maybe AF is coming early?  Too early to test, only 6dpo.