You're an ecto-endo, if that's even possible.
Why? Because a) you have the muscle-size of an ectomorph b) overall, there isn't much fat on you to be considered an endomorph, but there is enough not to be called a straight-up ectomorph. So, we combine the two and hey-presto!
My advice: Eat, eat, and when you can't eat, just eat some more. High protein and moderate carbs, with a little fat. Junk food is not the way. Good luck!