7 months pregnant please answer!!!?

i am 30 weeks pregnant and had an ultrasound at about 24 weeks give or take and the baby was breech i ask the doctor a couple of weeks later if i would have another ultrasound and he said as long as the baby was head first i probably wouldn't have another one i informed him that the baby was breech and he said they usually turn before time to deliver but if i don't get another ultrasound to make sure how will he know whether i will be able to have it natural or have to have a c-section i would like to know before i get in the delivery room so should i get another one or do you only get 2 throughout the whole pregnancy are you supposed to get any more this late in the pregnancy or do you get them all in the begining