Breast implant sizes vary wildly between manufacturers, so cup sizes are useless. Bring photos of the exact look you want to your surgeon consultation. Many surgeons won't use your images because they fear overpromising, but that's the best way to actually get what you're after.
I wish there was a universal golden, you know, bra that was in the British Museum that everybody used as a standard. There isn't, and every company is different. You go to Victoria's Secret, they're gonna, you know, typically upsize you because there's a marketing intent there. What I recommend instead is actually get pictures. Pictures worth a thousand words. So I say, okay, what does a full C look like to you? And then show me a picture. Let's get on your phone, let's get on Instagram. What does that look like to you? And then I typically use that for inspiration when it comes to sizing. A lot of surgeons don't like to do that because they don't want to overpromise. A lot of other surgeons make you sign ahead of time what your implant size is going to be. I think it's a little bit risky. It's just like buying shoes that you can't return. Let me know in the comments if you've had breast augmentation and how you came up with the perfect size.
