If your birds are laying, then at least 90% of their total diet should be the layer feed. I suspect you may be feeding too much extra grains, which dilutes the balanced nutrition of the layer feed and may leave the birds subclinically deficient in several nutrients, especially calcium. If your birds start a molt or cease laying, then it is recommended to switch to a starter/grower feed that is not so high in calcium. The higher protein in the S/G feed will also help them with feather regrowth. If your coop is insultaed, you may not need heat lamps at all. If it is not insulated but provides good protection, then you may only need one. Animals and birds have amazing ability to make physiological adaptations to cold. We humans not so much, so we anthropomorphize and think our animals need all these extra heat sources. Have you peeked into the coop at night to see where the birds roost in relation to the lamps? If they are close to them, then they are seeking the heat; if they are away from them, then the lamps may be too close to the birds. The mealworms are fine, though I might cut them to once a day just for economy -- they are pretty pricey!