My body has changed since we got together I used to be a fit size 8 and since having the kids I’m now a size 12 and definitely not fit, all flab!
@Momtot You just had a baby a month ago! I don't have kids but reckon a 12, especially immediately after that, is pretty good.
Varying between 3 dress sizes mostly within a healthy weight range I'd say is a normal variation even if you don't have a kid- a lot of us put on a bit then lose it again etc, I know I do, between a range of a couple of stone maybe.
It's not like you're obese or anything. I doubt your DH is bothered by that, and if he were he'd be a twat.
If were were previously a size 8, it means your body has changed significantly.
@Rybvita I disagree. It's not like OP is big now.
@Momtot It's weird if he doesn't kiss you during sex. 
It sounds from the comments he makes that he can't be arsed to try and make an effort to do things that'd make you feel happier. He just turns it around to claim it's a problem with you (which I imagine is hurtful and frustrating.)
He says you'll never be happy but we know that's not the case, as you were happy in the relationship for 2 years or more. Perhaps you could say that if he claims that again? It's not like you were only happy for the first couple of months.
It sounds to me like perhaps couple's counselling would help. Talking on your own as a couple you're kind of in a stalemate.
Having kids etc is a lot of upheaval and things could sort themselves out again, but his attitude isn't helping.
Things are bound to be difficult for you both after a new baby's arrived, with sleep etc, but you need support and warmth that he isn't giving.
His attitude is pretty shit/unhelpful TBH.