Howdy Alpha,
At 4 months old, it is unlikely that you are feeding him too much. However, his growth, when faced with such an abundance of food, will be accelerated. That’s OK, as long as nutrients other than proteins and fats are presented. Absolutely gut-load all crickets and definitely dust them with Calcium with D3 each feeding, or his accelerated rate of growth may compromise correct bone development and result in MBD. At around 6 months it is probably wise to slow his feeding down just a bit, perhaps no more than 40 crickets per day, along with introducing more greens into his diet. At one year he will need a diet that more like 50% insect and 50% vegetable matter.
I look forward to seeing his picture and I will give you further comments if his girth seems way too large.