Hi, Jules! I have just reinstated my full dose of plaquenil after six weeks of being put on half dose. The instant flaring I got in those six weeks was scary...my fingers "blew up" and my fatigue increased enormously. I have been back on the full dose for a few days and already am less tired, so I think you should go back to your GP and tell him how you are feeling.
Also, I have weakly positive ANA but not much else and my symptoms have lately been diagnosed as Undifferentiated Connective Tissue Disease (UCTD) , which you can google and see if it matches up with your symptoms. It is a mix of several disorders and I too get lupus rash...it seems to be strongly allied to lupus and is sometimes called latent lupus.
Hope this helps... I too am a teacher and it is that end of term time when you need all your strength and energy focus! Good luck and keep us posted.