How do I heal my depression/brain?

I've been suffering from major depression for most of my life. I'm on medication and have been for 10 years but it doesn't seem to help much anymore.
When I get really low I sleep all of the time and am basically non-functional. I'm pretty sure its a chemical imbalance because there is a lot of mental illness and depression/anxiety on both the paternal and maternal sides of my family.
I'm sick of it though. I really want to fix my brain somehow but I don't know how. I want to heal it somehow but I don't know what to do.
It's so hard because when I actually do feel good which is rare I am very grateful for it but I know it won't last long and then the feeling low comes back full force.

What's so frustrating about it is that I want to help people but its so hard when I'm constantly feeling so low and depressed. Plus it causes so much negative thinking for me its really hard for me to create a positive reality.
Does anyone have any suggestions on how I can heal this? Or do I have to live with this for the rest of my life? I want to be happy and help people but its so hard with this bringing me down constantly. Thanks