Bella,I had to have a dating scan done after I had a previous miscarriage and they wanted to do an internal but I refused nicely and asked them to do the normal one and then if that didn't work could they do the internal and they said that was fine.
I had the normal one done and I was 6w6d and he could see everything he needed to see.
I didn't want an internal one done as it brought back bad memories of the last one I had done when I had my miscarriage but if I had to have it I would have.

Its entirely up to you what you want done as it is your body.
All the Best
Michelle