Is my girlfriend addicted to ecstacy?

I'm afraid my girlfriend is developing somewhat of an addiction to ecstacy. We've been using about once a month for a while now, but now she doens't even try to keep a month or two between uses. We went to Nocturnal in Rockdale last weekend, and this weekend she went to Dallas and used both times. I know the harshness of the drug and possible long and short term side effects so I am able to control my use a little bit more than her. I've shown her all the facts about it but that doesn't seem to change much. I think it's the feeling she gets and then doesn't know how to party right without it. So, am I just freaking out or is she actually developing an addiction? Thanks.