Is it possible?

My last period started on March 11th and ended on the 15th. My boyfriend and I had unprotected sex a couple days after my period ended. He told me that he came in me a little bit when we had sex. Then about a week later my back started hurting, I felt nauseous, and going up his stairs made me so exhausted and out of breath. When I was nauseous I would eat a little bit and it would go away but then come back about an hour later. My back has still been hurting. I’ve still been feeling nauseous and i think my boobs may have gotten bigger and only the right one hurts!! I’ve also been fairly bloated which is a surprise because I’ve been working out almost daily and my stomach was fairly flat but not anymore. Could i possibly be pregnant?!