dont worry about it, shes just trying to find out if your like a player or something, by judging you on how many you've had.
but well you told her the number, its not like you can call her and say never mind i actually went out with so and so, whatever happened happened, how did she react to 9?
and also i dont really think it matters, shes going out with you cause she likes you, not because of how many you've dated, so dont stress it
now if she asks you how many girls you've had sex with, thats another story, i dont know about that lol
but for this topic, its nothing serious, dont sweat it
but anyways i think the lower number is sorta better, cause that demonstrates you can maintain a relationship, and aint girl hopping like other guys, also the quality of the girl also matters, i'd rather date a few really hot ones than a whole bunch of ugly bust downs