First of all.
How old is your snake?
Length?
Weight?
When they are younger they can shed up to once a month and as they age they gradually shed less and less.
The size of the meals also depends on the size of the snake. A good rule of thumb is feed it a rodent as thick as the snakes thickest part.
Sometimes snakes poop a few days after they eat some may not poop until a week after. So that may vary as well.