I'm an anti-ultrasound mama... I don't believe that their safety has been proven over the long-term.
That being said, I believe there is a time and a place for intervention. When I was 13 weeks along, didn't have *any* symptoms (didn't even have to get up to pee until the night I turned 13 weeks)... I went to my doctor - same one I had last time with no u/s, lots of refused tests, etc. It was a regular prenatal, but I told her that if she couldn't find a heartbeat with the doppler, I wanted an ultrasound. I think that scared her a little because she knew how much I was opposed to testing. Thankfully, she found the heartbeat and that was that.
But if I were in your shoes, I would probably want to get the ultrasound. Have you tried explaining to your husband the connection between a "good" labor/birth and mama being relaxed and comfortable with her surroundings? If you're going to be worried that there's something wrong with the baby the whole time, your chance of hospital transfer is going to sky-rocket!
If it's any consolation, I, too, have been worried about this pregnancy this time - as it seems many in our DDC are. I'm wondering if it's because we've seen so many mamas come and go with miscarriage - even late miscarriage? I don't know, but please do what is going to make you most comfortable with your birth experience... even if that means going for a test that you normally wouldn't get.