The leopard geckos i have are the first reptiles i have in my keeping, i have read as much as i possibly could, and yet found out that every book, reptile 'expert' is telling me different!! im confused lol

so, in my research i have found geckos are meant to be shedding 4-6 weeks, but i have not seen Maishu and Kai shed???? i have also read been nocturnal they can shed throughout the night, and eat their shedded skin, there are no remains or any signs they have or are shedding, my geckos seem dull, but they was when i brought them, their was 4 in a vivariam, and i brought two, i read that if kept in groups, or more than one, they wont be as 'bright' as they would when they were kept on their own??? is this true?
i have had my geckos for a month now - they are 7 mnths old, i have brought some moss for them, but i dont leave it in their, i have also attempted to bath them in warm water, to see whether that will help the process.
Maishu's tail is not as fat as Kai's, but heres the catch, i brought Maishu and Kai the same way i have them now, i have even attempted with putting 10 crickets in the vivariam, then taking them out before i go to bed, but quite alot is left, i have now decreased the amount i give them, Maishu seems to not be suffering, as she is eating, i know this as her tail is not getting thinner, it stays the same, she is longer then Kai which is probably the reason.
please help!!