Kimmy,
This may not seem like much of a comfort, but my husband says that most guys just don't talk much, and there was a time when he was like that, too. I do think that being "great with child" can be a part of why you are feeling the way you are, but I have seen the way your man looks at you, and talks about you, and there is no doubt that he loves you very much.
I read "The Surrendered Wife" years ago,(when our marriage went through its bug-on-the-windshield tough time,) and liked it very much. It is written from a practical, rather than scriptural perspective, but when Steve read it, he said, "YESSS! This is EXACTLY what I have been trying to say."
I would also recommend that you visit or revisit "The Five Love Languages." Sometimes the "we're drifting" feeling can come from either not acknowledging his primary love language, your own, or both.
Sometimes I take the direct approach, and try to lace it with humor, and will call him and say something like, "Hello, darling, are you at all interested in helping to diminish some female insecurity? If not now, may I make an appointment?" That way, if he is in the middle of dealing with the Dept of Transportation he can say so, and have some time to pray for wisdom, because God knows after 18 years, he still needs it!
Lastly, try and do your best to shift into what I call "Kingdom mentality" re: your relationship. This is tough, when you feel like you are just a beached whale of needs on steroids, but if you can get quiet before your Father and say, "OK, what do YOU need this to be like on my part, just for today?" He'll help you.
Kimmy, you are dear to us, and please feel free to call. As a woman in our church in Seattle used to say, "It's goan be awright, 'dem crookid places goan beee mayd strayyyyyt!" : )