Where best to find support for parents / carers of teenagers with anxiety and depression?
Probably the best place you could look would be to check out your state government web site / page for mental health services and on that page you will also find links to groups for parent support and links to other groups like GROW etc.
Another possibility might be to have a chat with your GP whether there are any local services to meet your needs.
If you cannot find anything and you know of.other people in similar positions to could start your own group. In one of my jobs (parish admin) I take enquiries from people who want to use our facilities for different support groups.
Hopefully some of these ideas will help you.
Welcome to the forums and thank you for being here. It's great to hear that you're looking for resources. I take it from your post that you are ideally looking for an in-person group?
Tim /Smallwolf gave some good suggestions. You could also look at contacting your local Community Mental Health Centre - a lot of groups link up here that aren't advertised widely. You could also try this link and then filter by your state -
Best of luck in your search