All female iguanas do not lay eggs. The male won't fertilize if there's nothing to fertilize. If their scales appear to have black around them, they have matured. As long as the base of their tail is pretty thick and they are walking fine and they are eating, they should be okay. You should bring them to the vet to get x-rays to see if they are calcium deficient in their bones and just for a check up. Best of luck.