oh wow! they are great numbers!! congrats!

i too was under the impression that dating scan was done trans...but i reckon if you voice your concerns to the centre (mention previous trauma etc) they might be able to walk you through it or offer an external. the only thing is that even with a trans it can be really hard to pick much up. at this stage (5-7 weeks) there might not be much to see (maybe a fetal pole/yolk sack...there might not be a heartbeat at this stage), but as long as you are aware of that and that the sonographer can go through with that for you you will be fine! some girls like to go at 5-6 weeks and then a follow-up at 9 weeks just so they can get a glimpse of the heartbeat for extra reassurance.

congrats again on those amazing numbers!