Hello Haier,
Your brief life story sounds a bit like mine. I have had a life long depression that may have started in my teens. Not diagnosed till I was 34 and had become what I thought was some sort of physical illness. My family doctor sent me for all kinds of tests over 2 years because he thought I would be upset if he said I was depressed. Found a medication that worked very well till a year ago. Then, it was back. I agree, it can be super hard to ask for help. I have this little voice that keeps telling me that asking for help is a sign of weakness. This is a place where you can open up a bit. There are plenty here that will understand what you are feeling and thinking.