talk to him! find out why sex doesn't seem as important to him as it was at one point in your relationship, he may be concerned about some harm coming tothe baby(unlikely unless it's a high risk pregnancy) Is this your first child with him, maybe he's not sure what he's feeling about the change in your body...but there's only one way you'll know, and if you don't talk it out with him...things won't get any better and will only become hampered with the addition of a second child, and the stress that brings, especially if you already have a child.

"but if he really loved me he would still find me attractive right?"

he should, he married you...as for your concern with his drinking, again, talk to him about it, but don't make it seem you are telling or expecting him to quit, if it was something he enjoyed before the two of you got married, there's no reason to expect marriage to change a person's habits...if you explain your concerns he should be willing to work out something acceptable to the both of you. It's admirable that you quit it all but don't expect him to do so...it would have to be something he wants to quit, not has to.

marriages take a lot of work, and most of the work is willing to express problems you perceive, work them out, come to some resolution and move on...children are just the tip of an iceburg in the difficulties of sustaining a relationship...so much of the freedom of a couple is affected by it, if you are both having to work a lot while going through all this, there may not be as much time as you two require to be a couple...complicate this with a pregnancy, an additional mouth to feed and it's understandable why he may be withdrawing from the relationship.

do something romantic for him, a quiet day in bed, a nice dinner, it's essential that the two of you keep the couple in your relationship while becoming married parents of children. make sure he's included in the pregnancy, have him go to a doctor appointment with you, see an ultrasound, talk about names over a nice lunch...

perhaps that's where the breakdown is stemming from, you two are too busy in individual lives, that there's too little time for the family life...so express your concerns to him...that's the best person to work out marital problems with.