You will find that surgeons don’t work in cup sizes. There’s no way they can guarantee you a certain size because a lot depends on your body type, height, weight, and frame. One size implant could be vastly different on you to another girl. Added to which, fake boobs look smaller than they measure due to the fullness, width, and position on the chest. You will get a better idea after you have had a few consultations with different surgeons.
Get a couple of pictures of boobs you really love the look of and think would suit you, and take those with you to the consultations. The surgeon will measure you and suggest a range of sizes they think will suit your frame. I say always go for the biggest they offer cause you won’t mind being a bit bigger than expected, but you may regret going smaller.
If it’s any help, i look about a D/D cup now and I had 380cc under the muscle x