I haven't had one since then either and I'll be 34 weeks Monday. my midwife says the less ultra sounds the better it means your baby is growing correctly and there's nothing to worry about!
Depends on if your pregnancy is healthy or if your having problems I get a lot of ultrasounds bc I am high risk and on a lot of medications but for a healthy pregnancy no you only get the one at 20 weeks unless you pay out of pocket and go to a place to get a 3 d or 4 d