What does the risperidal treat, is it an antidepressant? You have to be careful with messing around with your dosage by yourself, a doctor should ideally be the one suggesting you decrease or increase a dose. I wouldn't be surprised if your recent mood drop is related to you changing your med dosage.
You said yourself the risperidal made a HUGE difference so it's probably in your best interest to stick with it at the recommended dose. You could ask your doc about the side effects and decide if you're willing to put up with them for the positive effects you do get.

It's a shame your mood has become low again, I've very sorry to hear that, but try to hold on to that positive feeling, you know now you are positive of feeling "normal" and I'm sure that will return to you!