To be fair, although admittedly a nitpick, I will say I never said that the caffeine dehydrated you, just that the teas and tisanes do, the latter of which may or may not have caffeine.
That being said, I looked it up and yeah you're right. The evidence does seem to demonstrate that the diuretic effect of the caffeine in teas not substantial enough to really affect hydration levels.
However, it does lead me to wonder why my body seems to dehydrate if I drink more 2 cups of tea in a day. Like, it doesn't cause me to pee more (at least not more than an equivalent amount of straight water would cause me to pee); my body just dries out.
Thanks so much for the suggestions!
Unfortunately, as much as I'd love to try out Yorkshire Tea (I've heard they're amazing), they don't ship internationally, so as I live in the USA, I don't think that's an option for me. :C