My family is from the midwest, so not a new perspective I guess, but I would consider 6'/155 to be very skinny.

I'm 6' myself, and I thought myself quite skinny at 185lbs. It's the weight I'm moving back to now.

At 185lbs, I wear a men's medium shirt, usually.

I do have thick legs. I've always had big calf muscles and thighs, since I was a kid. Maybe that can account for 30lbs, I'm really not sure.