How does skin/flesh know when to stop growing?

Not looking at this situation with a gruesome example, I had a blister that was pretty deep on my thumb. When it started to heal(I pealed away the skin and new skin was growing beneath) you could see that it was rounded on the side that was untouched and the side which had the blister was kinda on an angle something like this, /0) (The zero being the finger nail so you are looking at it with your palm facing away from you). This made me wonder as it slowly started to grow back, how does your body know when to stop growing skin to even out and make the thumb once again round and not unproportionate? Why doesn't it just keep growing and growing until it's like a big goose egg? How does it know without a blue print that "okay this is the neautral and this is all that is needed" I hope someone can explain this, thank you and have a wonderful day.