Shifting half-step gearing is a little funny. If you go through all the gears in order, you have to shift both front *and* rear every other gear.

Another way is to remember which front chainring you're on, and bias your rear shifting accordingly. (i.e. if you're on the big ring now and shifting to go faster, go to a rear gear that's maybe a little to hard, knowing you can fall down to the small ring.)

Just something to think about -- some people adore half-step gearing but others can't stand it.

53 and 48 are pretty big gears for a double, especially for someone who claims to not ride very fast.

Two things you might consider:
(A) smaller chainrings (46/30 maybe?) and a normal-size freewheel (like a 24-14 or something),
(B) getting a triple with something like a 53/48/34. You could climb walls with a 34T chainring and 38T cog, if you could keep your balance that slow! :-D

Jan Heine has written this better than I can: http://janheine.wordpress.com/2012/1...ur-chainrings/