How do you properly thank someone for saving your life?

I'm a 17 year old high school student and my teacher recently saved my life. I was diagnosed with major depressive disorder when I was 16 and it hasn't been the easiest thing to live with...I felt like my parents didn't understand and my friends weren't there for me. Or at least that is what it felt like. I was lonely, scared, tired, and at times I questioned if life was even worth living. A few weeks ago my beautiful English teacher noticed that I wasn't doing well and spent her free time at the end of the day just talking to me. We talked for a little over an hour and it felt so amazing to finally have someone listen to me. This has been going on now since the middle of November. She has made me so happy and I feel so loved....I owe her my life. She has given me happiness and held me when I let my barriers fall. This woman is the kindest, most selfless person I have met and I am just so thankful to have her in my life. So how do I properly thank her? I always tell her thank you and write her notes but it just doesn't feel like it is enough. I want to show her how much I love her and how grateful I am for all the time she has spent with me but I really don't know how.