Okay, if you're just 15 feet, you can maneuver is a smaller space, with less inertia and momentum.
So before you get to the dock, head upwind quick and drop the main, maybe two boatlengths off, depending on wind speed. Then use the jib to get you back to a beam reach, then drop it.
Then let the wind set you broadside into the dock. Have crew fend off and use fenders if you have them. To correct your angle if the bow or stern is too far in, "scull" or pump your tiller to adjust.
It just takes some instinct, which comes with experience. You'll get there.
With a bigger boat, I would've agreed with some of the answers above about motor or kedge anchor. But 15 feet isn't going to hurt itself, or the dock, coming in sideways after dropping sail. As someone said above, it's an acquired skill since no one likes a downwind dock, but a fifteen-footer is an ideal size on which to acquire that skill.