I have not been diagnosed with any of the following things, nor have I been to see the doctor, or anybody, in general, about them; how can I(!?)

I have anxiety (social, general), maybe even agoraphobia, avoidant Personality Disorder & depression.

I know, I must get these things sorted-out, because, they are affecting my life, to say the least. I do feel very much inadequate, extremely sensitive to what other people think about them, and am very socially inhibited.

Not being able to go to certain places, or do certain things because of anxiety. I can't bring myself to do any college work, or other things, because I have absolutely no desire, and can't bring myself to do anything. In social places, such in college, I don't talk to anybody, unless I am spoken to first, in which case, I would reply with the shortest answer possible. I would never be able to get a job.
I am not going to university; because of the obvious issues of actually interviewing, and then the issue about the actual work and it being no where good enough, relating back to lacking any desire to do it. Even if I got beyond all of those obstacles, I wouldn't be able to live by myself, or even travel to there and back, by myself.

I get annoyed, because, the one time I asked my mother to find-out about seeing someone about this, she refused, but, she still complains about it, allot.
And it is quite evident, that there are problems, seeing as my older sibling is a very accomplished person, and I am the very oppersite.