Another ultrasound....

So I went for my ultrasound today to see if I'm having a boy or girl. My baby was curled up so the lady made me walk around and come back after 10 minutes of walking. When I got back my baby was still curled up, just had moved a little bit. So she kept trying to see and finally she said oh it's a girl. I couldn't really tell because she did it so fast, I think she was in a hurry because it already was over an hour of getting all the measurements they needed and then trying to see between the legs. So my question is can I have another ultrasound or do I have to go somewhere else and pay to get it done? Because I don't know if she was 100% positive my baby is a girl. I'm in Chicago Illinois of anybody knows what I would do or where I can go for another ultrasound. Please and thank you