Birth control implant

I got my implant nov.13 of this year

My boyfriend and I had unprotected and protected intercourse on dec.8

But I missed my period which was supposed to happen dec.16

I’m normally a day early or a day late

I’m now 13 days late but I’m on birth control with the implant

And I have also noticed bloated area on my lower stomach and kind of worried

I need help and information on what it could be

I’m spotting but every so day or for a few days in a row