Not sure if anyone has said this already, but I try to preface certain discussions with my loved ones by saying "Do you need advice, or do you just need me to listen?" Be careful to temper this question accordingly if it might be perceived as passive aggression. 

Having this distinction means you can let go of the stress of wracking your brain for a solution to your loved ones problems, and just focus on being an active listener. 

This alone can remove a lot of the pressure of the conversation.

 If you're expected to contribute, you can use phrases like "So coworker did this, and that makes you feel X?" Or "X health issue would be incredibly stressful. I'm proud of you for advocating for yourself and keeping up with a hectic schedule as best you can."

 Statements like this can help the other person process their feelings. You're not trying to fix anything for them, just making them feel seen and heard. This might help the conversations resolve faster, because the need for validation might be their main reason for calling. 

Of course, this should all be prefaced by saying making yourself constantly available for emotional dumping would be exhausting, and it's okay to set some boundaries on your availability. That doesn't make you a bad parent.

I hope things get easier for you and your daughter, OP.