Worried about pregnancy

So I got Nexplanon in the middle of November (first birth control I've ever been on) and I got my first period which I'm now on day 16 of 🙄 Anyway, in the last couple days I've noticed I've been pretty bloated and my boobs are getting sore (they used to get sore when I got my period before I got Nexplanon) and when I got my period after getting Nexplanon my boobs didn't hurt at all until now...on day 16 of my period. What are the chances that I could be pregnant? My boyfriend has never cum in me but we don't use a condom anymore because I have Nexplanon. I know pregnancy isn't likely, I just feel like it's weird my boobs are getting sore now and if anyone could give some insight that would be amazing!! Thank you so so much!!