It's important to get the right kinds of food, though there are no set times you have to eat. It's also okay to "pick", as long as you pick on the right foods. Opt for fresh veggies, over chips, whole grain bread vs while, etc. Try to keep a food diary in which you write down what you eat and how much. This will help keep you conscious of what you're actually eating.
Try to get as much exercise as you can. Put the baby in a stroller and go for a brisk walk every day....... getting some fresh air, might help him to settle better, as well as get you some exercise.
It is very tough to eat right and exercise if you have a fussy baby. I am on fussy baby #3 and she is now 3 months old and I have yet to lose the weight. First of all stop listening to people and media who tell you the weight should be gone by 6 weeks. In a perfect situation this may be possible, but not for most of us. Drink lots of water, that helps me. And try not to stress. Tell yourself he will calm down in a few more weeks (from experience its about 12 weeks that they start to be less fussy). For now take some time to write in a food diary and figure out a meal plan for when you do have the time to really focus on you again!