HELP!!! I haven't lost an ounce in a week. Where am I going wrong?

The closer you are to goal, the slower you lose. That's because a lighter body requires more calories to fuel at rest (your base metabolic rate) than a heavier one. At a heavier rate, your body may require 2500 calories, so eating 900 puts you at a defecit of 1,600 and you lose quickly. A smaller body may only require 1,500 calories, so eating that same amount is only a 600 calorie defecit, hence a slower loss.

Keep at it, and you'll get there!