Hi Meghan
I am sure that there are many tailors on here who would be delighted to make you a "long skirt" I hesitate to use the word kilt as that term generally refers to a mans garment and that is worn at mid Knee length give or take an inch.
There are lots of district tartans available and I am sure that learned xmarkers will point you in the right direction but why not go for the Walker Tartan. Many of us wear Kilts to which we only have the slightest tenuous connection. I myself lust after a Taylor tartan which is not my surname but my mothers maiden name. I dont have a direct clan connection on my fathers side, so grasping at straws I would chose to wear a tartan associated with my mother.
Good luck in your search and a belated welcome to the forum from across the pond.
Kind regards
Simon