Am i pushing myself? can running help you lose weight?? am i too insecure??

im a sophmore and i started talking to a freshman and a junior. i really like them both and they both want to hang out with me but i keep telling them i cant because i have plans when in reality i dont. i tell them this bc im very self conscience and dont really want them to see me. ive hung out w them in school but for some reason i think if we hang out after school like at a pool or something theyd see me differently because of my weight. i have a very slight double chin and i slight tummy. im 16, 5'3 and 120lbs. ive been told im at a healthy weight but i feel like i dont look like im at a healthy weight. i want a flat tummy. im on the volleyball team and i also am on the varsity cheer team at my highschool so i do get some type of workout at practice and games but would i be pushing myself too far if i have practice 6 days a week all year long and i start running everyday? like lately ive been wanting to start running around my neighborhood or something to lose weight before i hangout with anyone with summer coming up and all bc it is bikini season. and also does running even help you lose weight? what kind of things could i do to lose weight fast? i dont eat breakfast( i try to but i usually dont have time) i usually have a salad for lunch and then whatever my parents make dinner so im not eating unhealthy so idk why i look fat😬