3D ultrasound vs. Normal

So I am 36 weeks and will be going in for an additional ultrasound next week, courtesy of my doctor. We are hoping this will give us a better idea of the size of the baby. I know that many doctors will give you a 3D ultrasound of your baby, however mine does not unless there is an issue with the baby I think. We had paid to have them done at 27 wks somewhere else. do you guys think there’s a way for me to convince them to make it a 3D ultrasound though?? I really want to see my baby like that one last time before she is born!! now that she’s fattened up.