That's the classical period piece I played for my audition. Yes, it looks easy, but if you play it well, it's very impressive because all of the dramatic changes, in dynamics and notes etc., even in the first page. Are you playing the whole Sonata or just the first movement?
Rach, as always, gives excellent advice. Also as painful as it is, try it slow with the metronome, like really slow (60). Try just a measure at a time til you get it right. Do you practice finger excersizes? Those will fix any technical problems you may have. I had particular trouble with measures 43 and 44. The professor that heard me play says in measures like that it is helpful to keep your wrists high, then the fingers like "dance" below. Try it.
Good luck...Try not to get yourself too nervous :-)