Wanna BET you have a Q tip catching this paper OR some other obstruction that sometimes catches the paper the wrong way?
Check inside your toilet tank and look for the water level line.
Located normally 1″ below the over flow tube.
If your not getting full volume (especially today with the 1.6 GPF) your paper maybe getting lodged in the crown weir of the internal trap. Personally I would opt for a plumber to come out an AUGER this fixture just to make sure nothing is partically blocking this fixtures discharge opening.