Just FYI Wintergreen is the flavor of Life Savers Breath Mints in the Green Package, Spearmint is in the Blue package. Peppermint is like the red and white "Starlight" round mints.
Since you like Peppermint, I would start with one of the Peppermint flavors from this page:
Menthol & Mint Flavor Concentrates.
And get some of the Polar Blast from this page:
Additive Flavor Concentrates
Try the peppermint at maybe 15%-20% (I use Wintergreen at 17%) to start and focus on just getting the Peppermint flavor where you want it. Then focus on the "coolness". You can add the Polar Blast a drop or two at a time and adjust until you get the right "cooling".
I would make no more than 10ml sample sizes until you get the recipe right.
NOTE: I use Polar Blast by adding just 10ml to a 236ml bottle of liquid. So with this stuff a little goes a long way. OH and whatever you do, do NOT try the Polar Blast straight or put a drop on your tongue...TRUST ME.