Implantation bleeding or PMS?

Moon

Around 10-13 dpo I spotted and thought I was starting my period but I only spotted a little bit and it stopped. I was supposed to get my period yesterday according to calendar but didn’t. I just had CM only. Today which is 15dpo, I bled light pink and my underwear was rusty color when I wiped and it stopped again. Is it my period coming or implantation bleeding?