How can i avoid eating too much? sometimes i forget to eat breakfast, then i end up with eating lunch too much.

Consider fiber bars: You answered your own question by saying this happens more if you forget breakfast. If you don't get around to breakfast you can try a nutrition bar rich in fiber and protein; be careful to avoid ones too high in sugars. See http://tinyurl.com/pplmoq7 for good choices. Eating bars high in fiber with water or tea before lunch will be filling. Nuts such as almonds are also a good snack before lunch.