Hi Anony,
First, I would like to welcome you to PC. You will find alot of caring and compassionate people here, always willing to help.
I'm so sorry you have had this depression for so long. I started having depression at age 14 and am still battling it and I'm 52 now. That's a long time. My whole family, including my Mom and Dad, which now are both deceased, have fought depression. I don't know if it is the hereditary thing or not.
Are you on any anti-depressants? If not, you may want to try them. I have been on them for eight years now, and probably wouldn't be here now if I hadn't gotten on them.
I'm sorry your Mom and sister also suffer from depression. It sure doesn't help your situation.
You might want to seriously think about finding a Therapist to talk to. They do help. Plus, you might find new ways to cope and then you could pass that on to your family.
I do hope that you will start to feel better soon. Please come on any time you need to talk. We are here for you and will help in any way we can, even if it's just a gentle hug~(((((((((((((((((((((((((((((((((Anony))))))))))))))))))))))))

Take Care,
Linda