Is this a healthy diet?

so for breakfast i have a small bowl of special k with hilo milk, for morning tea i either have nothing or if i'm at school or just really hungry i'll have an apple and a petit miam with are those tiny cups of yogurt, for lunch i have either a chicken salad or a wrap with lettuce, cucumber, cheese, mayo and if there is any chicken. For afternoon tea i'd have either a banana or a small bowl of yogurt, for dinner i have no power over that but my mum usually cooks some form of meat, some form of potato and either salad or veggies. If i'm still hungry after dinner i'd have a small bowl of yogurt. Is this a good diet? What could i do to improve it? thank you