Something really important to remember, and your psychologist, psychiatrist or therapist should have told this to you right off the bat, that depression isn't necessarily CAUSED by anything. It doesn't have to be a life factor.
You have to think about it scientifically. Your body, for one reason or another, developed a seratonin or dopamine defciency. It is no reflection on your life, lifestyle, or of your level of personal happiness. It's just a hormone fluctuation. Your body was not producing the hormones to the level necessary to keep you going within a normal range. Prozac is now providing that missing hormone to restore the chemical imbalance in your brain.
It's like asthma, or cancer even. Something in your body is jacked up, through no fault of your own, and you need medication to help fix it. Depression is not something you can just "snap out of." It's not having the "blues." It is a mental illness, and you can't fix an illness by snapping your fingers.
I would be wary of going off Prozac since it is working so well for you. Make sure that before you begin to taper off ( and remmeber to do so VERY slowly, Prozac has alot of withdrawal issues) make sure you have this approved by whoever is dispensing/supervising your medication. Make sure that they are on board with you. My NP, who supervises my meds told me she needs me to be in a normal, happy, healthy state for one year before we can work on tapering off .