Let's Do This!

Hi! I'm a 24 year old American women living in Japan.
I've been struggling with weight-loss my entire life and have health problems because of it.
Instead of doing anything about it, I let it become a depressing topic that I have ignored for years and years.
I've finally become fed up with myself and my situation, so I'm trying hard to lose 100 pounds.
I'm over 200 pounds right now but thanks to My Fitness Pal, I'm on the path to success!

Is hoping to lose 100 pounds by the end of the year anticipating too much?
I'm limiting myself to 1700 calories a day and exercise for at least half an hour every day with dancing (Just Dance for the Wii!) and walking around town. I tried doing only 1500 and 1600 a day but my cravings got so bad, I started binging and ultimately, sabotaging myself.

Umm, anyway, nice to meet you!