Help me please!!!

So my period ended 6 days ago but my nipples are discolored they look bruised. They have never did this before I’m also feeling super nauseous, very emotional and I’m feeling off. Me and my boyfriend had sex last night and he said it was tighter than usual like really tight would that have to do with anything. I’m almost 18 and we live together we have sex almost everyday I’m not on birth control and we don’t use condoms he just pulls out. Is there anyway I could be pregnant?