Ultrasounds? How many have you had thus far?

Ok so my husband is in the military and I've had different Obgyns for all of my pregnancies... well this pregnancy I've had a stroke and been diagnosed with MS and they have ONLY done 2 ultrasounds... the first was at about 10 weeks bc I was bleeding  and then at 24 weeks for gender... they said they will not do another UNTIL IM IN LABOR?! What the heck I've never heard of that? Idk if I'm just super emotional but I would hate to go into labor and labor at home just to get to the hospital and be told I need a c section... I'm on my third VBAC and almost lost my first son (my first pregnancy) bc he was transverse trying to deliver... had anyone been told the same? Or have they done the positioning scan before you go into labor?