help!!! worried

So I'm on the skyla IUD and I normally have pretty regular periods since it has been put in 4 months ago. Now I'm late. I've have a sight pain in my lower left abdomen pelvic area almost like I've pulled a muscle and bloating. Me and my boyfriend have sex almost every Friday. We don't normally use a condom because I'm on BC but I never let him cum in me unless he has a condom on. I took a pregnancy test and it came back negative. Is there a chance I could be pregnant?