Damn, same here, although I'm pursing graphic design as more of a hobby/side work for money rather than a major.
My foray into graphic design started similarly to yours: the first time I ever did anything "graphic design-ish" was when I made someone a sig in the ASM. Before that I was a huge sig whore here, going into various sig threads in general (when they were still around), grabbing as many freebies as I could. I didn't even end up using most of the sigs; I just wanted them.
Therefore, wanting to learn how to make these elusive sigs myself was a natural urge of mine. I went through every last tutorial I could find on Pixel2life, using a different one for each sig I would make in the ASM. The process was: Google an image, follow a tutorial to make a cool background, slap on the image, follow a tutorial to make some cool text, and post! I get better rather quickly, and didn't look back.
Eventually I was accepted into the SSM (reborn), and I made sigs there for a short time. That was my first real "accomplishment" in terms of graphic designing; I got to join as a member of an elite Internet thread. YES!
It didn't end there, however. Knowing my way around Photoshop was ridiculously useful for school, such as when doing "artsy" projects (I could and still can not draw, so using Photoshop worked perfectly).
In fact, I even entered a local science fair with a project regarding the uses of Photoshop in science and won first place in my category. I also joined my high school newspaper, become the layout editor, and made that shitty paper look like gold.
Graphic design = hell yes.