Jennifer,
There are so many different reasons why people SI. No matter what your reasons are, there are other people who have similar reasons and others who have different ones. Try not to worry about what the textbook answers are. For one thing, text books don't have the whole story - they don't even claim to. For another, you are yourself, an individual. Nobody is a text book case - we are all unique. Trying to conform and fit the text books won't help anyone.
Therapy does need to be nonjudgemental, but people who feel bad about themselves or something that they do might project their own judgement onto the therapist and feel judged. That might be something you would want to talk to your therapist about, along with the pressure you feel to conform to other people's reasons.
If anything that I have said is helpful to you, I am very glad.

Best wishes to you!
<font color=orange>There is an easy answer to your problem that is neat, plausible, and wrong.
</font color=orange>
__________________
“We should always pray for help, but we should always listen for inspiration and impression to proceed in ways different from those we may have thought of.”
– John H. Groberg