Implation bleeding?

My period was due the 22nd and hasn't came all tho I started spotting last night but it's been on and off and pinkish with brown sometimes if I was to be pregnant I'd be 4weeks5days is this possible? I've been slightly crampy with sore boobs and have ewcm as well with and before spotting, I know implation happens before missed period but I've read it can happen after as well that's why women mistake it for their period. Glow isnt telling me much just keeps moving my period date 2 days ahead when I make down late