I do not carry spare magazines. I carry a spare gun instead. One in my waist band. One in my pocket. If I am just carrying my pocket gun then I do carry a spare mag. I have a mag pouch that my wife made me out of neoprene from an old pair of waders, with an attached clip from an old cellphone holder. It looks like a cell phone holster.
No matter how many times you do it and nothing happens it only takes something going wrong one time to kill you.