How can i lose just a bit of fat on my stomach and thighs?

im 14 underweight by like 5 pounds-140 on empty stomach, 5'9" im thinking, i have a little fat around the stomach area, abs are not "rock" solid but their hard but dont show, my thighs never bothered doing anything for them yet, but i do about 50 crunches/situp on a weight bench that is slanted and take a minuter or two rest then do 50 more, and so on i usually walk 30-50 minutes before or after doing crunches let me know which is best, used to walk about 6 hours a day but i cant becuase no longer allowed in the sun doctors orders and now im nocturnal because of it. i do count calories about approx 1000 a day sometimes none at all or less as im not very hungry ever, yes i do know that im only fourteen and you might say not to worry you'll still grow, wrong i have smoked for about two years weed and cigs, cigs stunt growth as i didnt know that until recently try to stop about 3 weeks ago, now ill smoke them if somebody else offers or has one available, i'd like to have my abs show, ive gotten drunk 3 times so it aint a beer belly obviously but id appreciate it if anybody could help me with this, maybe also a diet i could follow. Thanks.