Why am I not fat even though I don't have a healthy lifestyle?

I was wondering that despite not exercising (excluding walking around campus) or eating health I'm not overweight. Sure my tummy and thighs are squishy but I'm not fat. Ever since I had my depression phase when I was 13 I rarely eat, constantly sleep, and stay inside all day. I'm now out of that phase but I'm rarely hungry, love sleeping, and have no desire to be outside in the humid air of my state. Despite all of this I'm not fat, I rarely get sick, a doctor said I have the healthiest eyes ever, and I didn't even fracture my bones when an iron gate fell on my foot. I'm not complaining, but I'm very curious as to why this is.