3 Fat Chicks on a Diet Weight Loss Community - I feel so lost. An Introduction.

Hello there,
This is not my first post. I've lurked on this site for a few months now but have never introduced myself. My name is Amber and I'm 17 years old. Let me tell you a little bit about myself.
All of my childhood up until now I have been very slim. I never gave a thought about my weight, what I ate, or anybody else's size. I simply wasn't aware of the concept of weight at all. My entire family is very thin. They all run and have very active lifestyles. We have only ever eaten home cooked meals, full of fresh vegetables and fruit.
About a year ago, I suddenly piled on 20 pounds. I say suddenly because I never even saw it happening. My complete lack of awareness prevented me from noticing anything until I looked in the mirror one day and didn't even recognize myself. I remember vividly lying awake in bed one night and feeling the fat on my stomach for the first time. I was terrified, not because it was fat but because it was alien to me. It wasn't part of me and I couldn't get it off.
I don't do things by halves. I am controlling, I am a perfectionist. I threw myself into research on diet and weight loss, and suddenly a whole world, that I had never even known existed, was opened to me. Within a few months I was 118lbs and beginning to see myself once more. I was happier. My family complimented me on my weight loss but not directly. They smiled and told me how great my skin looked, how proud they were of me exercising and to keep doing what I'm doing. I've never spoken to anyone about my weight or diet. As far as they know, I am still in the dark.
A few months ago, before Christmas, I slipped for a few weeks. There were parties and a lot of food and it showed on the scale. I lost the control I had mastered. After Christmas, I vowed that I would get back on track and finish what I had started. I was very upset with my regain and found myself at about 122lbs.
Since then I have been on a diet relentlessly and have consequently gained 6lbs. I am either at one extreme or the other, eating impeccably or binging ferociously. Binging is only something I have discovered ironically due to dieting. My binges are disgusting. Only ever lasting one day, they are enough to wipe out an entire week's efforts with an additional pound each time. And that has been the cycle for the past number of weeks.
I am not overly restrictive. It is not extreme dieting. I am simply obsessed with food. I spend the entire day thinking about it and counting the time down to the next meal, even if it consists of boiled vegetables. I have never eaten below 1200kcal in a day.
At the end of June, my family and I are going on holidays and I have set that as my deadline to finally rid myself of this burden. I am determined but I still overeat when I am not at school. I feel so angry at myself I want to scream. I feel like I am emotionally and physically destroying myself. This past week has been especially tough, resulting in me for the first time, purposely making myself throw up my food after overeating. I have done it two more times in the past week. I feel proud and relieved afterwards. I know it's wrong.
I understand that my story may sound irrelevant when there are people with much bigger problems on this site, but this is so real for me. I don't know what to do and I feel so lost.