Yeah, I agree with the too gentle part, but you could probably ramp it up to medium, with finger tickling, and see how that works. I don't know if she'd like you really digging in, some like that, some don't. But honestly, some girls go crazy more from normal tickling than from the really agressive stuff.
I hope you do some nylon/pantyhose tickling in the future! Tickle her in a fancy dress in flesh colored pantyhose and see how she reacts!
Actually, good work so far, she's really pretty, and I'm glad she's cool with it. Does she have a tickling fetish herself, or is just indulging you?