My husband and I were virgins until marriage, so I understand about the pain thing, as my body was also not used to having sex. When I met him after a few months of separation (as we live long-distance for the present time), it also hurt more too. It really helps to use plenty of lubricant, and to make sure that my body is sufficiently aroused (with plenty of foreplay) before we can have intercourse. Without enough arousal, sex would be really painful. But as long as there is lube and foreplay, I am good to go... and sex is very enjoyable. I wonder if this would help your situation. Maybe your husband didn't spend enough time to turn you on before penetration, which might have caused him to not to be able to enter properly.
Another issue is that there is a condition called vaginismus. It is when a woman subconsciously tightens the muscles around her vagina, and the man is not able to penetrate. The woman isn't doing it intentionally, but it just happens. In many cases, she unconsciously does this due to stress or anxiety. (I am a med student so I read about this sort of stuff.) You might want to read about this condition and see if it applies to you. Having enough foreplay, or having your husband do something relaxing for you (massage, etc) might help reduce anxiety towards sex. Another thing that might help (something I like personally although I don't have this condition) is to let me be in charge of my husband's initial penetration. He will give me oral first, and when I'm ready for him to be inside, then I will grab his penis and insert it myself. (When he inserts it himself, he pushes it in too fast and it can sometimes be painful, so I like to control when he gets to insert, and do it at my own slow pace. Once he's already in, then we can have intercourse at any pace without it hurting at all.) That's just another idea which might help it hurt less for you.
As far as your previous comments about weight, I know that a large proportion of men do care about their woman's weight. It does seem that husbands tend to be a bit more forgiving overall compared to boyfriends. In my case, I am significantly overweight (though trying to lose it), and my husband is at a healthy weight. I was obese when I met him, so I know he still loves me for me. We have talked about my weight issue, as it worries him. He tells me that he loves me so much that he doesn't want to spend a day of life without me by his side. So it bothers him if I am eating myself into an early grave rather than creating a healthy long life together. Even though I know my husband would be more attracted to me if I lost all the weight, nonetheless, we still have a great sex life. He has never punished me for my weight by not wanting to get physically intimate, and he loves to touch me. Similarly, when I met my husband he had a flat belly and nice biceps. He's gained about 10 pounds, and still at a very healthy weight (I actually like him better at his present size as he was slightly thin before and now his face looks even more handsome). But the weight gain is fat, not muscle, as he has gotten a little belly pouch now and somewhat lost those yummy biceps as they were bigger before. Although I miss that and don't want him to get too much belly fat (as it isn't good for his health either), I also still love intimacy and closeness with him and nothing changes that.
I don't know if your husband's issue is one of his not being sufficiently physically attracted to you because of YOUR weight, OR it might be HIS weight that is causing him problems. Heavier men are more likely to have low testosterone (higher estrogen), so it's possible his sex drive is reduced for that reason alone. It could also be that he is more tired out (as weight does that to you), or it could be early cardiovascular issues (resulting in less blood flow to his nether regions - though I think you guys are probably a bit too young for that, though it's still possible). So there could be many causes to explore about why his drive is decreased. Nonetheless, despite the sex, I hope there is still plenty of cuddling and affection in the relationship, as not being touched by one's partner can feel like terrible rejection.