hi there i had mine done a week ago,and had 560cc over im 5,3 and 8 stone and at the moment in a sports bra which is a 34 DD but i was a 34 a i also went for high profile because i want roundness at the top, but thats all about personal preference. i think you will be def a D/DD when done.
And dont worry its not as bad as you might be thinking i have not had alot of pain.
you will be fine. and as for losing weight i dont think will make much difference as for under or over that depends on what look you want to acheive ie under being more natural. . hope this is of some help x