I think running is definitely the best/easiest way to get/stay in shape. That's a shame you cannot do so in your neighborhood. Could you run after school or perhaps there is a jogging club at school?? Is there a park you could run in that would be safer than your neighborhood? The one thing I recommend with running is to really push yourself. Decide how far you want to run and do it, do not stop and walk, slow down and pace yourself but don't actually switch to walking. Time how long it takes you and each day or week try to improve on that time.
Maybe you could ask for a gym membership for Christmas??
At home I would think crunches or jogging up and down the stairs would be somewhat helpful.
In regards to eating healthy I recently switched from a very junk oriented diet to a very healthy diet. I don't eat ANY fast food. I also cut out soda for several months and ONLY drank water. I took a liter bottle of water with me in the morning, finished it by lunch, then had another liter in the afternoon. After several months of drinking water with no soda I tried a soda at a restaurant and it tasted gross. So if you force yourself to eat healthier foods for a few months your tastes will change and you will lose the desire to eat junk.
There are lots of tasty snacks you can get but I was not trying to lose weight so I cant really recommend the best things to eat. (Though you can't go wrong with fruits and vegetables)
I think it is good you are conscious about your weight and health at a young age. If you start to work out and eat healthy at a young age those habits will continue into adulthood and it will be easier to maintain the figure you desire.
I'm sure there will be people who tell you that you look fine, you are not fat, etc. Just remember it is YOUR body and if YOU want to look a certain way don't let other people discourage you from doing so!!!
Best of luck!!