My Psychiatrist wants me to consider ketamine. [California]

I have suffered from major depression since I was young. As the years go by it seems that my symptoms get worse. I have tried almost every SSRI there is as well as a few antipsychotics with minimal or no luck as far as relief from this debilitating illness. I currently take the maximum dosage of three different medications for my depression. My Psychiatrist recommended I start researching ketamine because that is basically the next step for me. I am at a point where I feel like this is as good as it gets for me and I'm doomed to feel this way forever.

Anyways, I guess what I am looking for are experiences with ketamine for major depression and also if it was covered by insurance.

Thank you