I Am Absolutely Terrified Of Putting On Weight. Am I Suffering From Eating Disorder?

hi, i'm 15 years old, 5 foot 2 and weigh 94 pounds. i think i could have an eating disorder, i always skip breakfast, lunch and only have a small dinner. i only drink water because it has no calories but only drink 1/2 a cup a day. when i'm in shops or deciding what to have for tea i always look at the calorie and fat content. when i stand infront of a mirror i see a massive stomach, huge thighs and big arms. i end up lying to everyone, saying i have already eat when in fact i haven't. my mum keeps saying soon i will be anorexic and i have awfull mood swings. i'm terrified of dying but i think if i were a lot thinner then people and my dad would like me that little bit more. i used to weight 9st and whenever i ate anything my dad would make a comment about it but then a few minutes later my sister would get loads of things to eat and he didn't say anything to her. i use the scales about 7-8times a day and if i have put on weight it uts me in a really bad mood then i won't eat anything the next day. i am absolutly terrified of putting on weight but i'm scared if i don't i could die. please can you help me?