Bad money managment?

[Sniiii]

Hey guys. I've been playing poker for 14 months now, and I've read a few good books which have taught me a fair amount. In general, I'm a winning poker player and I'd put myself quite above the average player.

As such, I put in 50$ at Pokerstars, and started with fullring NL10. Played my way up to 140$ and proceeded by going 6-hand. At 220$ I thought I'd test the level of NL 25, and have been doing well there. At this very moment, I'm at 280$ (started NL25 today).

So my question is, is this bad money managment? My roll only allows me to buy in roughly 11 times which really is not a lot. Should I go down to NL10 again, even though I feel relatively comfortable at NL25?