Some of the ladies have done some films so you could try to google yo see clips and size, I know of 3 currently in dublin with some amazing clips.
I do think who ever you chose providing you talk to them about your concerns they will be as gentle as possible, I met star a while back who is large but with some care and time it all slotted into place with no bother. And I think once your over the initial shock you'll be surprised how accommodating you can be.
Mind you there are some who would bring a tear to your eyes.
Good luck and let us know how you get on.