I don't play much 25NL short handed, but at the higher stakes, aggression wins. If its folded to me and I hold any playable hand (I'm talking Ax, Kx, 2 cards higher than a 9, suited connectors, 1 gap connectors and pp) I'm raising 3-4x the bb. You may be camping too much and not playing enough hands. You have to be able to call down and bet out your mid pair sometimes shorthanded. When first learning the game I would only play one table at a time and get profitable at that before I add more tables. Another thing you have to be able to do shorthanded is adjust to your table and play the players a lot more. If you know someone is raising with BS you have to come over the top or check raise them with your good hands. If the table is tight, steal a lot of blinds, if its loose, check/raise a lot and let the other players do your betting for you. Hope this helps, try posting some hands for review, or even a session if you like.