Hello.
I am not sure if you could complete your question, but I will try to help with some information.
First of all, I encourage you to review your post here and note how many times you have written 'self-downing' words, sentences and beliefs. This is probably the most important clue to what has been happening to you.
You may be depressed, but it can only be confirmed from a formal interview and some psychological testing if indicated. You may be experiencing dysthymia, a form of depression where the symptoms are not obvious or severe and are there for a long period of time. The diagnosis is not so much important here as the need to reflect upon your life once again and find out your 'self-defeating beliefs'.
Psychologists, psychiatrists and researchers over the last few decades have discovered the power of the subconscious mind. Whatever you tell yourself constantly becomes your reality eventually. Thoughts, repeated constantly, tend to manifest in the physical world.
This may be a good opportunity for you to think about your beliefs. You may be carrying irrational, self-defeating beliefs which you will need to modify and convert them into rational beliefs. You will probably need the help of a psychotherapist. Additionally, understanding the problem won't help much unless you decide to act on the new beliefs and change certain behavioral patterns.
Depression can be hereditary. But the fact that your mother also has similar problems should not make you feel helpless. Avoiding the use of technical terms, I would encourage you to use pen and paper to jot down your 'self-talk', write down what areas in your life you want to improve in, and write what action you can take to see the change. This is one exercise you can start doing right now.
Hope this helps.
Regards
This post is for the purpose of providing medical information and is not a substitute for a face-to-face consultation with a doctor. This post is neither intended to give or rule out a diagnosis, nor to create a doctor-patient relationship.