I would actually recommend you follow up with your pediatrician again. I would suggest you have your thyroid hormone levels tested. Low thyroid levels can present as increased weight gain (despite "normal" food intake) and poor energy levels. It can also contribute to depression type symptoms. Pseudotumor cerebri has also been reported to occur with hypothyroidism.
Certainly eating healthy and moderately is important but I think, given your history, you should consider looking into some of the medical reasons for weight gain as well.
Advice and opinions given are based on the information provided and must not be considered an official medical recommendation. The limitations of the internet prevent an appropriate evaluation. Always consult your doctor if there is concern.