I fit all of this in an old Patagonia vest pack.

Tippet Spools (2 to 4 depending upon where I am fishing)
Fly Boxes (2 to 3)
Platypus Water Bottle
Scissors/Hemostat combo
Nipper
Split Shot
Floatant
Indicators
Tape Measure
Tiny Flashlight
Hook File
Small Compass
Waterproof Camera
Cliff Bar
Dried Figs in Zip Lock Bag
Waterproof bag for phone and keys
Leaders
Small Kleenex Pack
Tiny disposable lighter wrapped in plastic
Rain Parka if necessary
Swiss Army Knife in my pocket