smaller
My wife is 5'0", and was frustrated by "standard" sized paddles because they felt so big and clunky. She ended up with a small-shaft Werner Little Dipper. The smaller blades make the paddle more comfortable in the water, and reduce the swing weight. The smaller shaft makes it easier for her small hands to grasp.
Smaller blades don't mean that you'll go slower. Using a paddle that's too big is like riding a bike in a gear that's too high -- it feels like work, and you tire quickly. Using an appropriate paddle lets you paddle much more efficiently and comfortably.
A paddle that's too long feels heavier, and makes it harder to paddle in a straight line.
Several companies now make paddles with smaller blades and/or shafts.
I would certainly agree with the folks suggesting that you also look at boats better matched to your size. A boat that's too wide and too deep will be difficult to paddle comfortably. It'll force you to hold your arms up which will make them tire sooner.
One boat that you might find used would be the Perception Carolina 12XS, which has also been known as the Carolina 12.0 and Umiak over the years. You might want to replace the seat with a piece of foam, but it'd be much better suited to your size than what you're in now.
http://perceptionkayaks.com/carolina-12-xs
If you want something a bit wider, the Acadia Scout might work:
http://www.paddling.net/buyersguide/showBoat.html?boatID=1819&boattype=Kayaks
A newer option would be the Tsunami SP:
http://www.paddling.net/buyersguide/showBoat.html?boatID=1954&boattype=Kayaks
And there are many other choices that might be more comfortable than your current boat.