Calories & Dieting

I recently started a diet. In my diet I basically eat three times a day. My breakfast is usually a protein shake (100 calories), my lunch is something low fat like baked chicken or a low fat sandwich (350 calories), and for dinner is a protein bar (180 calories). For dinner I even occasionally eat a small meal, kinda like my lunch. If I get hungry, I usually eat some saltine crackers, beef jerkey or drink tomato juice....I try not to ignore my hunger pains. Well if you add the calories together, I end up eating less than 800....and my friend is totally freaking out about it. My first week I lost 8 pounds. My doctor had put me on a 1200 calorie diet....and I have learned that when I watch my calories I never get anywhere close. I really believe I am losing weight safely and that this isn't a health risk. I feel great, Im not weak, I have energy....and I work out. I just need another opinion....I want to know for sure that I am doing the right thing.