Early AF?

Kira • TTC 1st for 15mons and I finally had my BFP!

Today I am 11dpo and I woke up this morning and had brown spotting. I read that implantation could be brown, or it could be af starting. Which is so annoying that so many symptoms are the same. I ovulated 5 days earlier then glow predicted this cycle, and now if af is starting it would be my shortest cycle in the last year. Af is actually due 4 days from now. I haven’t had any more spotting, and no typical CD1 cramp signs. So I don’t know what to think. After 13 cycles of bfn I won’t test until af is late, so it’s just a waiting game. Any one have brown spotting and got their BFP? Or do you think it’s probably af?