Are you at your goal weight? If so, perhaps you should just relax and enjoy yourself. If you maintain a healthy diet and exercise program, you shouldn't have to worry too much about gaining the weight back.
I know, but I just can't help it. I start thinking about how much did I eat or best way to burn the calories
It sounds like you're setting yourself up for an eating disorder. Maintain a diet and exercise diary, then you don't have to worry so much about how much you ate or burned off - you have it right in front of you.
Make sure you're eating enough healthy fat, with every meal to satisfy your hunger, because that keeps you fuller longer...