Remember, we don't experience the physical changes and the bonding that comes with having a child inside your womb. We have no basis to understand that.
Third Trimester is a good mark of where we, as fathers, really start to kick into father mode. We start to see things in our house that need to be addressed. We start to get the baby room ready by painting, carpeting, or whatever else mom requests fo us.
And he goes to your appointments with you, and you are complaining about him not being interested?? I went to all my wifes appointments, and from what I saw very few men were following my lead. All of my wife's friends were shocked that I refused to miss an appointment.
If I were you, I would show him how much you appreciate that he is doing that for you. The majority of men out there certainly don't do that, and for you to say he is not interested in the same post where you acknowledge that he goes to your appointments seems a little harsh to me. He actually deserves your praise and some oral fun as well, in my opinion.
Seriously, give it some time and before you know it he will be spending hours with his hand on your stomach waiting for one small kick or flip.