A few photos from different angles would help. I'm old enough that the internet wasn't useful as a source of info and I ended up with a clinically obese corn snake, she ended up so fat that it resulted in her refusing food for three months despite the fact I made her swim around the bathtub for 15 minutes every day. I can honestly say that I know what a fat corn snake looks like.

I suggest checking around to find somewhere that has adult corn snakes on show, if your corn is wider than every other you see then its a good bet its fat. I haven't gotten any more corn snakes since I got so used to having a fat one its difficult to get past the fact that at a healthy weight they look skinny to me.