My boyfriend has lied to me a lot about just little things about his past?

Me and my boyfriend have been dating three months. He has told me he quit school when he was 16, and he was from new jersey. Makes sense, the accent and all. His sister died of leukemia and his parents split up so he found a job in north carolina, (here). I just saw an old facebook of his, from 2009. There were pictures of him in 2008, I can tell it was in North carolina, not new jersey. And i could tell it was in his moms house i have seen in pictures. His mom even mentioned on her facebook she lived in NC for 6 years. He told me his parents divorced after his sister died. He told me he graduated from a high school in new jersey. I just saw where it said he went to a school thats in north carolina. He told me not to mention his sister (that died) around his family. They didn't like for people to mention it. He also told me he lived with this girl before, that she was 20. I saw her facebook and shes only 17 now. We are 19. And read his messages and theres no way they could have lived together . I only snooped because he seemed to be lying. Why is he doing this? How can I confront him without seeming like a stalker.