I had an internal done with DS at 6wks as they couldn't see the baby (was even difficult with internal) however I had an ordinary u/s at 7wks with this one without a problem got to see the heartbeat and everything. A friend of mine had a dating scan by internal and was told it was more accurate and meant that there was less chance of not seeing anything = extra stress. I would ask for an external if you feel really uncomfortable about it but they aren't that bad