Yes, I'm certain that the Enneagram is among the least scientific personality systems, but I find it useful as a tool for organizing information. I guess, to me, it's analogous to taking music and splitting it into the categories we have for it -- rock, classical, et al. Arbitrary, but handy, and with its own degree of truth.
For instance, your experience in high school can be described as a manifestation of the classic Five terror of being absorbed by alien entities, and thence losing independence.
I'm often reluctant to share my ideas...they're such a personal thing to me, as if they were extensions of my body, and had their own pain receptors fed back to my brain. They're my offspring, and I can't stand for people to criticize them...but, like children, they have to let out into the world at some point, or they won't ever do anyone else any good. Because ideas combat each other with the weapons of logic, developing T has been very instrumental for me -- I can both defend my ideas better should they encounter danger, and make sure they are more prepared not to run into trouble before they exit.