Some people can burn carbohydrates more efficiently than others. I'm currently on 50,30,20 (pfc) and I've had good results. I'd definitely try lower carb first as that has the best success rate. If you have trouble putting on muscle I'd add in more calories 200 at a time.
Your appetite can be directly linked to your metabolism and so that would be my guess as to why you don't feel like eating any more than you are. The best way to increase your metabolism is to eat more and more often (ironically), which will in turn increase your appetite.
Here is a diet plan which equates to about 2800 calories (50,30,20) (protein,fat,carb).
Meal 1: 4 eggs + 1 piece of toast + 40g protein shake
Meal 2: 230g meat + 200g vegies + 50g rice
Meal 3: 25g almonds + 40g protein shake
Meal 4: 230g meat + 200g vegies + 50g rice
Meal 5: 25g almonds + 40g protein shake
Meal 6: 230g meat + 200g vegies + 25g + almonds (no rice)
Add to that a quality fish oil, a multivitamin, and probiotics for digestive health. All weights are uncooked and 'meat' refers to anything lean (chicken breast skinless, lean beef mince, tuna, etc). Veggies excludes potatoes - just stick to green fibrous like broccoli. Protein powder must be low carb as possible (no sugar). Drink plenty of water (at least 3.5 litres) but not on top of a stomach full of food!
Remember, its mostly about FOOD. As well as all this, you should be training about 3 or 4 times a week and HARD. Train every set to failure. Record your reps/weights and ensure you are always adding reps or weights (ever increasing intensity). There is a lot more to it all but this will be a good start. 15-20 reps on the compounds like squats and deadlifts will burn the most fat whilst growing (or at least maintaining) muscle. Forget cardio - and forget situps.
It sounds like you already have a grasp on listening to your body. At first you will feel like you are forcing food in and intuitively you will feel like you are eating too much. This will quickly change as your metabolism gets up a gear. You will enjoy sustained energy levels throughout the day.