Don't worry. Your weight is fine.

At 130lb, and even at 122lb, your weight is fine - neither too low nor too high.

You say you're aware of calories so I will tell you that you're supposed to 2,100 calories a day for somebody your age (and more if you're exercising). Are you eating anything like that? Because eating too little can also stop weight loss as the body slows down its metabolism to save energy.

You say you gain weight from eating ice cream. Is this a temporary weight gain (1-2 days later) or a more permanent one? Fats take longer to digest, but if you are restricting your intake a lot it is also possible that your body is taking the foods you eat and converting them straight to fat.

You say your problem spot is your stomach, perhaps you could start doing crunches or something to tighten the muscles there?

It also might be worth having an appointment with your dr and being reassured about your weight. He could also give you tips on healthy eating, too, for somebody your age.