Has anyone else found their $ex life has dropped?

I'm 34 weeks pregnant and I'm still pretty fired up and ready to jump my boyfriend at most opportunities (sorry, not a very eleoquent way of putting it really) but he just doesnt seem to want too :( He's told me he's a little scared about bringing on the birth of our baby and finds it uncomfortable because we're restricted with positions too. I'm open minded and have made suggestions but I'm now starting to feel fat, frumpy and undesirable. Has anyone got any suggestions or should I just leave well alone till our little one is born and my body starts to go back to some form of normality?