How do I lose ten pounds? not overweight... just self cautious...?

i'm 113.5 lbs and my BMI is exactly 20.00 and I want to lose the weight because i have gained it all in like, 4 weeks, and I'm worried that if I don't get it off, i'll gain another 10 lbs.. also, I walk about a mile a day, and jog very slowly 1/4 4 times a week. then for breakfast i normally have a bagel with peanut butter and jelly, for luch just like a cookie and hot cheetos, and after school i'll snack on anything salty, then i will have like 4 oreos or something then i will have dinner of chicken and brocolli or something. so yeah thats about what my diet is like most of the time. I don't get much execise only because i have so much HW this year.... so yeah.... how do i lose 10 lbs?