I've bought & sold quite a bit of American Fostoria, and I've purchased enough Indiana Whitehall to say that I'm 99.9% sure your glasses are Indiana. American pieces do have a more distict flare then yours.
As Toby pointed out in his article while Fostoria made some colors in their American line, a vast majority of this line was made in clear. If it is color I usually think Indiana first.
There is a big difference in the glass quality, and in person I can usually get it right based on that. Also as Toby pointed out, if I'm in doubt on clear I use the blacklight test, Fostoria turns yellowish, Indiana doesn't.