Nexaplon Question:

So today was the day my period was supposed to start, I got the implant about 3 weeks ago and my doctor said I’d more than likely have a period this first go because my body clearing out all the stuff after having a baby(3 months postpartum). The doctor said I should use protection for the first week of the birth control, I did but I completely forgot once. Should I test or do you think it’s just the implant taking my period?😅