Ashie,
I totally understand where you're coming from. My family also ate very unhealthy food and since I didn't do the shopping and all of that stuff was in the house, it was hard to control. When I left for college and was put on the meal plan, I actually lost weight, lol!
My advice, similar to yellsa's, would be to start small, so it's not so overwhelming. If you drink soda/juice/milk, etc, cut it out or at least way down and drink water or seltzer (calorie-free!) instead. That's probably one of the easier ways to save on some calories without really trying to change what your family buys or eats, which can be very difficult. Also, maybe see if you can get whoever shops to buy some fresh fruit for you or even some carrot and hummus and snack on that rather than chips or whatever else is laying around. Most importantly, don't starve yourself! Your body will just freak out and you'll end up binging!
Good luck! Poke around in the forums, there's tons of great advice here
The beginning is always the hardest
I know I'm young and still a kid but I'm tired of being unhappy with myself and my weight and I don't want to keep living my life feeling so unhappy and never doing anything about it, When I first took a crack at losing weight I was desperate I ate nothing but bread and water and tried to make my self vomit
(always unsuccessful in my attempts thank goodness) then I would just starve myself but that would only last a few days before I ate like a cow as the end result 
when I get so motivated to work out and be a health guess what I pull, I pull the 
