I must confess I find it slightly unnerving that your instructor has encouraged you to rely on PAPI lights so early in your training.
A crucial part of learning a good circuit is getting comfortable with the different visual aspects you should be trying to achieve at different stages around the circuit, the most important of which is the final appraoch.
Penguinas point about using a mark on the windscreen to help you line up is a great one for learning and can be used at even the roughest and untechnically advanced farm strips!
I'm not wishing to sound harsh but that is my opinion.
On the subject of the flare, just aim to fly the aircraft down the runway at about two feet of height with the power off. If it trys to sink keep squeezing back on the stick untiul it just gives up and puts the mainwheels on the tarmac. You won't jar your back and you certainly won't get a bounce using this method. Just before the mainwheels touch you should hardly be able to see much of the runway ahead of you as it should be obscured by the engine cowling.
Good luck with the rest of the course.