I know that feeling. Sometimes I'm restless coming up with a solution when my daughter seek my help.
If it's her studies, I can easily hire a tutor if I don't know the subject considering she's a science student and I did arts.
But with other life problems, I kinda direct the problem back to her in a twisted version. From her response, I'll know how to go about her problem.
There is no way we can have a solution ready at all times. You are doing your best and that counts a lot. To be able to walk through her problem with you by side is comforting as it is.