I'm 32 weeks pregnant going on 33 weeks, and my daughter isnt moving that much. She only moves when i drink something really cold and lying on either of my sides for like a good hour and then she will stop moving for the rest of the night.
Was she always really active? My other two daughters weren't active at all, so the counting that they have you do sometimes didn't really apply to us. This pregnancy the baby moves A LOT, so I would be concerned too. But call the doctor. They'll check you out.
I'm not a doctor, but I believe its normal after so many months they slow their movement because they have less room to move. Go ahead and ask your doctor, it will at least reassure you. But I'm sure your fine. If she stopped moving completly I would worry. But it sounds like she still moves, just less often.
It is common for your baby to move less when you are this far along, mostly because there is less room. If you are worried then do a kick count. I think it's 10 kicks in 45 minutes means that it's probably okay.
If you are really worried then call the OB in the morning. They' most likely ask you to do a kick count or ask you if you've done one recently. They may ask you to come in just to be safe. Try not to stress though. As I said, she just has less room now so she can't quite do the gymnastics that she once could.