Perhaps your mother is frustrated with herself for not being able to help you.
I know how you feel about not wanting to talk to anyone about the depression. You're already fragile and vulnerable. You're afraid of how the other person will respond---if they will reject you. I guess that's why it is probably better to talk to a professional or a religious leader if you have one. I know keeping quiet feels safer but if there is something you can do to get better you can't do it on your own. I hope you get the help you need.