Breast revision to fix gap? (Photo)

27, 5’4 and about 52kg. I currently have 325cc HP,started with next to nothing. my implants are 7.5 years old now, i have waves of loving them and waves of wanting to fix my gap and go a little bigger. i feel like i still look flat chested in a lot of tops still because of my gap, looking at getting 400/425cc. I've naturally got a dent in my chest so I'm nervous I won't be able to achieve this but also don't want to go too big as I'm quite petite as onr surgeon recommended 475cc to fix the gap