Hiya Vicky,
I am having Mr Singh on the 30th July too
so we will be there at the same time!
Sorry I can’t help you with your size but I am only having 340 unders as have nothing to start with 
From what I have read on other posts if you already had boobs and have lost the volume then you need a bigger implant to fill them back up rather than like me as he will be practically making them from scratch!! lol
Are you on SoFem? there are a lot more ladies on there and you will get more replies to your question and the girls may share their pics so you can see the differences in size to give you an idea.
Good luck and roll on 30th July for both of us 
Marie xx