Ed: Here you can hear my lowest recorded singing yet
I would say if you can get to low 2nd octave regularly, you are probably a baritone. I can always get to the low 1st octave, but I lack the weight that a bass singer has. That being said, I know people who experience the same problem of losing lows when singing highs. It's possible that your voice just adjusts to singing in a higher range rather than lower.
It has less to do with the notes you can hit, but rather the weight and comfortability you have in hitting them. For example, anyone can whistle-voice a C6, but they won't be considered a soprano.