Also be prepared to NOT see a heartbeat as in such an early stage of pregnancy it sometimes isn't happening yet. Mamas get a terrible shock which they then have to recover from and yet it's a perfectly healthy baby just too little for the heartbeat to be showing. Are you sure you need an u/s? If something isn't right with your baby (which can't really be seen this early anyway) there isn't anything anyone can do. Sometimes u/s cause more distress than they prevent from this kind of thing. We also don't actually know for sure that u/s exposure is safe for babies and the vaginal kind puts the waves even closer to the developing embryo than the kind done later. It's worth researching all this a lot before you embark on it. How comfortable, or otherwise, the experience is for you largely depends on the skill and care of the operator so if it hurts just ask them to go easy.

This is what Dr Sarah Buckley says in her book "Gentle Birth, Gentle Mothering" in a very finely researched and referenced article on u/s.

More recently, ultrasonographers have been using vaginal ultrasound, where the transducer is placed high in the vagina, much closer to the developing baby. This is used mostly in early pregnancy, when abdominal scans can give poor pictures. However, with vaginal ultrasound, there is little intervening tissue to shield the baby, who is at a vulnerable stage of development, and exposure levels will be high.