I agree with 3D's question of what makes something lesbian. Does it have to even involve ANY lesbians? Forgive the seemingly stupid question. I wonder because Primetime writes a number of stories (specifically thinking about the "Ticklish Nerd" series where none of the people involved are lesbians but all enjoy tickling the nerd to numerous orgasms.
Not to push my own stories, but my Competition at the Office series involves tickling and a competition between women to see who can "force" her "opponent" to have so many orgasms, she has to admit defeat.
If on the other hand, you are looking for stories that contain not only erotic tickling but the emotional elements of a relationship, that is clearly another topic altogether. Probably Tiffany would be a good writer to check out. I still love her twister tickle story.
Still, if you are simply looking for f/f tickling, check out Anna and Heather stories. Seeing that you are new to this site as this is your first post (unless you've been lurking), I would suggest looking at previous stories and seeing what you like. For me, that was half the fun-- if not more.
Anyway, welcome and enjoy.