Dear Liz:
I imagine when you feel anxious about a particular issue with one of your teenagers, you think about fixing his/her issue, correct? It can help if for each issue, as you start feeling anxious, think: what, if anything, should I do about it?
If you figure it is best you do nothing at the moment, then do nothing. If you figure it is best you reach out gently to your teenager with: how are you feeling about this? And depending on the answer, proceed or not, do so.
When you find yourself with no plan of action, nothing to do, you can say to your fear: nothing for me to do, so there is no function to you. Hopefully, functionless, it will dissipate, disperse.
anita