Worried af

Sep 15th I had sex on my period, my bd came in me while I was on it, I take progesterone only birth control pills and I’m not the best at taking them but I do, I’m also still breastfeeding and I took 3 of my bc pills the day it happened. However today I started spotting dark blood, in 10 hrs if only spotted little to nothing, my period isn’t supposed to start until the 11th of this month…

I’m extremely concerned, could this just be a side effect of taking that many bc pills?