Implantation or early period? Help!!

First month off the pill.. had protected sex with condom and pull out method.. I know my chances are slim but I’m worried because my period is 2 days late and I have my usual back pains that I get right as my period is about to come but I’ve never had light spotting.. it’s a light pink and brown. i know I ovulated on the 21st so I’m 15 dpo.