I have had a few too, with previous loss & the to make sure all was gone...

I have a dating scan this Friday (but I'm around 12wks already) so it will be external, I initially saw the probe & thought OMG, but it's really painless & everything is covered so it's not like they can see anything...

You'll be fine & I'm sure they'll do external first & then if they cant see anything they will recommend an internal each time they have tried externally with me when i was losing blood etc & ended up then saying to be sure we'd like to do an internal etc...