One handed but it is killing me lately. So incosistent, at times when I am in defence I really don't know what to do. If I slice I leave a "cookie" to the opponent, if I play flat it is not very consistent.
I learned from start to play one handed and too lazy to learn two handed .
I am old school, I still find 2handed bh a "girlie" shot .
I have a similar problem, though my backhand drive is more effective on defence. I am having trouble putting away short balls on that wing though, just very inconsistent, and if I can't run around to hit the big forehand I usually hit a slice approach but of course this gives my opponent a chance at winning the point when I should have put it away.
As for your trouble on the backhand defence, obviously apart from practicing your passing shot more, in matchplay hit more lobs and also the short slice cross-court leaves them a difficult volley and I find they almost always put it down the line which is perfect for your running forehand or hit a drop shot which you can pounce upon.