Don’t worry about it too much, each snake is on their own timeline. You might also have just not noticed a shed, especially if you have substrate. Some snakes end up crumpling their shed into a tight ball which might be accidently thrown away or lost when cleaning).
I don’t know that this is a cause, but snakes sometimes delay shedding if they don’t have enough moisture. If your humidity is low and/or you don’t have a water dish that could be a factor. But, it’s likely just normal.