That's a "shooting pouch." A "possibles bag" is for carrying all the stuff you need that is NOT associated with your gun and is generally larger (like a haversack). But it's yours, you made it, and can call it whatever you want. Nice job too. It looks like deer hide to me too.
I think the definition is regional.
I have always heard Possibles bag used as all the things you could possibly need for your gun
capper , caps , patches , turn-screw , spare flints in a flint wallet ,tiny napping hammer spar nipple if a cap lock , wedge puller & nipple wrench tool, cleaning jag , ball puller ect.. as we got to hunting closet to home I suppose it became a shooting pouch with just what you needed to hunt for the day
other than your powder horn.
all your non gun stuff when in your haversack, or other means of transport like saddle bags, pack basket or canoe pack.