I think SARAH gave you good, sound advice. You want to lose weight and stay healthy, and since you've already had trouble with motivation, it's better to start out with a more sensible plan. Focus on lean meats, lots of veggies & salads to fill you up; whole grains & complex carbs in moderation; plus some fruit & dairy each day is good too.
You can always tweak your plan as you go along, but getting started is half the battle won. Maybe start with interval walking (regular/fast), toning exercises (pushups, situps, lunges, squats, jumping jacks), and some weight-lifting would help you too ... good luck!