Most of that weight you have lost is water weight which means you are dehydrated and your health will suffer.
10 pounds of fat is roughly 35,000 calories. If you are eating 500 calories, that means you are roughly 1,000 calories deficient. Over 11 days, that would be 11,000 calories or about 3 pounds in fat and muscle. The other 7 pounds is water, which is almost an entire gallon. Once you stop this HCG, your body will restore all that water.
500 calories is too low and will also likely effect your health. I recommend you seek the advice of a qualified health care practitioner who specializes in weight loss.