General consensus seems to be backpack or saddlebag if not carrying much. Racks and pannier(s) of you need to have more. See if you can leave the books out (are they available online or as PDF?). Also try to leave the lock out (can you leave it on the destination rack?). Then you can lighten your load up somewhat. I personally just do the backpack for now (Columbia Cresent Peak 23L).

Edit: I left out the handlebar bag. Maybe a decent sized one might also suit your needs for commuting?