Keep playing your 25NL game and cross the bridge when you get to it. Who knows? Maybe by the time you have the bankroll for 50NL, you'll be ready for it. Maybe by that time, going up to 30-40 buy-ins will increase your comfort level and you can play your game.

You said you weren't too comfortable at 25NL (even though you're crushing it). Nobody said you HAVE to move up to 50NL at a certain number of buy-ins. When you get up to 30-40 buy-ins...open up three tables of 25NL and one of 50NL. Then slowly increase the number of 50NL tables you have open (this is if you multi-table, of course). Good luck in your poker conquest!