Poker Variance

At the moment my poker game is in a swing. I'm trying to make the switch to shorthanded limit play at limits of 2/4 ... but I think I'm making a few too many mistakes and its costing me in variance. At times I feel pretty comfortable and then I start having problems and lose my comfort level. The problem I think I'm having is shorthanded involves far more close decisions. Stuff like what do you do with bottom pair facing a bet on the turn ... it can't be correct to throw that away every time. But I'm having trouble figuring out the right conditions to call there. The variance is causing my bankroll to fluctuate by a hundred dollars up/down ... and I know poker is high variance so I should expect this. I can't stop having the feeling that I'm making mistakes though ...

Heraldk