Pregnancy after depo

Hello. Im new to this group.

I was on the depo for a year and couple of months. My last depo was sept 2017, which finished in dec 2017. I started getting my periods properly in june 2018.

I already have one child an suffered two misscarages after. So im hoping for our rainbow baby. We have been TTCing since june.

I went to the loo this mornin and have a brown spotting. My period isnt due for another 4 days.

Do you reckon it could be implantation bleeding ? Or am i over thinking it ?

Thankyou