We have used a protein shake and mct oil which increases the total daily calories to 1000 and have had good success with the hcg daily injections. (subcutaneous in belly fat). The protein shake (we use UltraLean by biogenesis) helps to balance the blood sugars throughout the day so you don't have the spike and crash which can leave you feeling hungry all day. The MCT oil promotes the fat loss and also helps somewhat in balancing blood sugar throughout the day.
I don't know if you up your calories with the food what would happen with your weight loss, though. Maybe you could try upping your protein to 4 oz and adding another veggie (from the approved list only) to your meals?
Also, you can get ketosis test strips from your pharmacy and check to see if you are in ketosis. (Fat burning state). If you are not in ketosis at all that can explain why you are struggling so much with the diet. (If you are not metabolizing your fat, you are not being "fed" so would therefore be hungry. It is your metabolized fat that is supposed to be nourishing you while on the hcg diet. The 500 calorie diet is for your fresh nutrients/protein so you don't get deficient in anything.)
If you are not in ketosis, it might be that you have a bad batch of hcg that is no longer potent. Or you could try cutting out the tomatoes and fruit.
Hope this helps.