I don't east breakfast or lunch because i don't have time, and when i get home to eat dinner i eat half a serving and become full but extremely guilty?

Eating disorder?: It sounds like eating is a big issue for you, and that you're controlling how much you eat/don't eat. The "extremely guilty" when you do eat is worrisome to me, because food is there to nourish us rather than torment us. Please see a psychiatrist or therapist skilled in eating disorders, so you can get help before this goes further.