Bulimia??? I'm just soo tired of it?!??!?!?

okay, so, i am 4'9 and around 70-75 pounds about 5 months ago i checked and i was 68, but i'm sure i've gained. okay, so for normal school days i have a small bowl of cereal, then a salad saltine scrackers and sometimes a cookie and chocolate milk for lunch, and then a regular 400-600 calorie diner. to all of you who are gonig to say i am too young to be thinking about weight, EXIT THIS PAGE. i'm not here for your critizisum, just your help. at night i am usually VERY thirsty because i don't get thirsty during the day, so i would drink right before bed less then 1/2 of a water bottle, but, i am guesing that wasn't smart since in the morning the water is still sitting in my stomach and i fele bloated. i am small, but i am constantly bloated and uncomfortable, like right now. i don't wnat to become bulimic but i am so tired of being so uncomfortable and bloated, what should i do, maybe wtaer pills? i know that i have a lot of water weight and am constipated, i dont need medical attention