Do I have to be a certain age to buy anti-anxiety vitamins (kava, etc)?

I'm only 16 but I have severe anxiety/panic attacks, and as desperate as I am to be relieved of this suffering I looked into benzodiazepines, but I don't want to get hooked on something like that. That would be horrible.

Would it be possible for me to have access to other (natural) anxiolytics? The thing is I already read up on herbs/plants like kava, valerian root, etc. but would it be impossible for me to show up in a vitamin store and just buy some? I mean it would make sense to me if the answer were 'no' because they have some kind of effect on the chemicals in your brain (and kava has been known to cause liver damage after long time use, but I'm not interested in using it every single day), but then again they are just vitamins.

I just want to drive to the store and discretely pick something up because I don't want my parents to get worried... and knowing my mom she'd probably try to put me into therapy. Thanks for the help