Have to wait to find out the sex

Is anyone else's doctor making them wait until 21 weeks to find out the sex? We thought we were finding out at our last appointment and were disappointed when they shut us down and told us we have to wait another month because that's the way they do things there. They want to be able to see everything in that one ultrasound and are only letting me have two for the whole pregnancy! They are very nice there, things like that have just upset me. Makes me feel like they may be a little impersonal? I dunno, maybe I'm just whining, but they've gotta know how important and exciting these things are to a mother, especially in her first pregnancy. Should I be upset?