You are doing fine. Listen to your doctor's/nutritionist's instructions. I hit 1000 calories on week 3...but everyone is different and some doctors encourage patients to eat less.
My group wants 1000-1200 as soon as possible....but they don't start pushing you to make this goal until you're 6 weeks out or so. They just encourage you to do your best. Take your time, listen to your body. Do your best to make your fluid and protein goals first, then worry about calories. Best wishes!