For those who had chin surgery, how many millimeters?

Even though the correction was over, my chin didn't improve as much as I thought, so I went for a consultation today. There is no one in Daejeon that is known for doing chinless surgery. I was thinking about going to Seoul , but I saw the initials in a photo report of someone who came to Daejeon as part of a plastic surgery clinic from Seoul. I did a search and called right away and got a consultation. I think I had a consultation for about 50 minutes. They said my chin is not short, but it's just underdeveloped in the front. So I didn't remove it from the bottom (it makes my face look longer or bigger). They say they only remove it from the front... 6.5mm. I was wondering how many millimeters they usually used . And I have a straight and flat jawline...ㅠㅠ I want to have a v-line... but they say I need to pull the implant down a bit in that case... I heard that my face is getting bigger.. would it be better to listen to the doctor? I would like to ask for advice from those who have done it.