How can I tell if he truely loves me?

He is my fiance. We've been engaged for nearly 2 months. We're both very young. He is 17 and I'm 18. We want to get married in 1-2 years and we've been together for a year already. We still haven't had . I know this is weird, and there's more. When we met he asked me for immediately and I told him no, not yet. So we did everything physical except for and focused on other parts of our relationship. We don't have TOO much in common, but we enjoy being with each other. We don't call each other, unless we're going to hangout. We go out sometimes but mostly hang out at home. I believe him when he says he loves me, but I've always been a skeptical person. I sometimes wonder if he has some motive? Like I know we've been together for a while it doesn't make sense, i don't see what he could possibly get out of this if he didnt love me, but im paranoid about it sometimes. He does little things that bother me. When im over sometimes he will not speak to me or he will just seem to want physical stuff. I've gotten upset about it and started crying before and he didn't seem to care. He would be like " Oh jess." and not say anything else, or do anything. I feel like he should care more, we're getting married. Shouldn't he want to hear how i am and care about me? or am i expecting too much? Should I believe him when he says he loves me? He does a lot of sweet things for me to show he cares, but half the time it's like i'm alone when i'm with him. He doesn't understand why i get upset. i ask him about it, but he tells me what i want to hear, regardless if it's true or not, so i'll never know. What do i do?