17 weeks still don't feel baby move

Mary
This is my first pregnancy and I haven't felt the baby move at all yet. Should I be concerned? Could it be because I don't really know what it's supposed to feel like? At this point where would I feel the baby move if he is moving? My next ultrasound is in 3 weeks from now but I might go crazy with all this anxiety till then. I'm constantly worried that something might be wrong