Advice please!

I know this is a mans group, but I need a mans perspective. Please no bashing for the age gap, but I’m 28 and I’m dating someone who is 47. We’ve been together since last June and currently I’m 28 weeks pregnant with our little girl. When we first got together, everything was amazing! The sex was great the affection was there, it was perfect. Over the last 3 months I feel that everything has drastically changed and it’s so upsetting. I can’t tell if it’s me over thinking or my hormones being in high drive or there’s something really wrong. I feel lately I have to initiate sex and still then he doesn’t want it. I’m lucky to have sex with him once a month. Mind you, my sex drive is super high. Maybe his testosterone is low or maybe just his age? I don’t know what it is, but it’s making me feel so unattractive. If I bring it up to him, he gets a little defensive and says that I’m just seeking attention. I really care for this man and I want this relationship to work not only for the sake of our daughter, but I really want it for us too because I love him. Please any advice would be appreciated.