Possible implantation bleeding?

So I need some help please! My period is due in 5 days and I did have unprotected sex during the week with the highest chance of pregnancy and did not know. I am not upset if I am or upset if I’m not I’m just trying to figure this out. I have been lightly bleeding all day. No cramps maybe mild cramps in my stomach normally I have intense ones in my back. It doesn’t feel like a period at all. Normally my first day is super heavy. I found a calculator that says if this is implantation bleeding it would happen.. today actually and I would be 9DPO 😦 thoughts? Opinions? Thank you in advance ❤️