No more ultrasounds once I reach 3rd trimester?

Is that normal? My ob said that it wasn't necessary for another ultrasound to be scheduled. But how would I know if my baby is breech? How would i know how my baby is growing? I haven't had an ultrasound since 22 weeks and I'm now 30 weeks. I don't want to be one of those mothers that finds out last minute that I need a c section... and she's not willing to schedule another ultrasound.