Baby is really small so they use transvaginal to get really up there, & yes the baby should be surrounded by a sac and the heart beat ia heard between 6-9 weeks
You can't see baby on a regular one until about 9/10 weeks
Because you are early in the pregnancy I had one done my first time
I had to have two transvaginal ultrasounds because my uterus is tilted they can still get heartbeat and everything else they can in the regular one