I not hungry and starting to eat less now?

Two weeks after summer started my friends and their parents stated noticing I'm getting taller and skinnier.I still weight the same but I only grew a inch. I am now 5ft and 6 inches weighing in about 125 to 127lb. The only thing changes was I stop going to Karate when the school year ended which is on May 27. I usually eat healthy food like seafood, vegetables and fruit.I rarely eat red meat and when I do it is usually like once every two months. I eat fast food only once or twice a week. Now for the past week I starting to notice I'm eating less. The only time I'm eat a lot is during lunch. During breakfast I started to only eat something like toast bread with peanut butter and jelly instead of a omelet and in Dinner I eat really little because I'm not hungry. I sleep like 2 or 3 in the morning until 9 or 10 a.m. I ask my father about it but he doesn't really know why. I can't ask my mother since she is in a different state right now. I'm not depress or anything. I am usually home alone since I have no siblings nor relatives. I practice dancing or Karate every night for 1 hour and do solitude things everyday like painting or cleaning. I hang out with my friends like once a week since I don't like to be bother that much and like to be alone. Is my body out of whack or something? Or is it because of my sleep.