I kind of understand although I don't know if you are looking for responses...

I think she thinks (although it's just a guess) that volunteering will help you focus on something other than depression...which is true, but you have to be in a place in your depression that you CAN go out and volunteer. It's not doable when you're in a deep dark hole. Heck, getting out of bed is sometimes an achievement.

I also worked in a nursing home for quite a while and, while it is fulfilling, you can get get burnt out pretty quickly. At least I did. You do, after all, see people at the end of their lives and you have to know that you will go in one day and someone will not be there... Someone you may have become attached to.
So you must be able to be emotionally equipped to handle a nursing home (not to put anyone off, but this IS a depression forum).

If you are considering a volunteer position, please make sure it's something "manageable" for you in your present state.
Hugs and I hope my words don't cause offense to anyone.