I had a rough time at the end of my pregnancy with DS. I was HUGE - he was 11 lb 6 oz at birth and I felt every pound carrying him at the end. My feet were swollen and I could barely walk because my pelvic bones were out of whack (chiro really helped with that, just in case anyone goes through it). I worked until 10 days before my due date. If I had it to do over again I'd have quit work much earlier.
Just because we struggled to get pregnant doesn't mean it's any less hard for us then it is for fertile people. Infertility does not take away your human card!!!! You can be grateful for pregnancy and still be miserable!! On another fertility board I participate in, pg women are slammed if they dare complain about anything. It infuriates me to no end. Fertile people kvetch all the time about being pregnant. We are no less than they are. We can carry gratitude in our hearts for pregnancy, but I think it's okay to recognize that there are plenty of aspects of it that are kinda crappy, especially when you get near the end.
So for whatever it's worth, I think it's okay if you are miserable. Wear it proudly