will it be easy to do this? im quite slow when it comes to losing weight. so far ive been trying to lose weight for a few weeks and have only lost 3lbs (dissapointing). my 16th birthday is on the 29th september and i wanna look my best becasue right now im a complete state lol.

is this a reasonable target? how much excersise will need to do? so far i walk home from school, i spend fridays at college where i do alot of practical work outside, saturdays im kept busy at work with dogs. i do sit-ups and things at home, then theres p.e at school.

for food, i think i must consume 1500-1800kcal a day not too sure.

breakfast - cereal
snack- low cal crisps ie. quavers or snack a jacks
lunch- sandwich, (only butter and then like ham or something)
dinner (just the usual like spaghetti or soup or chicken or woteva lol)

im gunna start making more variety like salads or pastas instead of sandwich and crisps for lunch and then some healtheir option for dinner, im not sure.
sorry this is so long lol.

are there any other changes i should make to my diet? how much more excerise will i need to do, to get to my target weight??