I taught myself to type too. It's funny because people think I type ridiculously fast (120WPM last I checked on a typing program), probably partially due to the fact that I play piano...but I'm straying....
I will forever use my right thumb to hit the space bar. Reason being that my first keyboard was an odd one. It was fine and all, but the space bar was odd. It was two keys down there. The right thumb was the real space bar. The left thumb was a backspace key. I can use it just fine, but people who use strictly left thumb or people who switch back and forth hate my keyboard with a passion.
Jam it back in, in the dark.