I never had that problem when I was on the pill. i actually had less discharge. Maybe everyone is different, I think you should consult your doctor.
I personally have had more discharge then normal but I did contact a nurse and she said that was when you were ovalating......
Sometimes, birth control pills will throw off your bodies hormones and cause an overgrowth of yeast. Depends a lot on what the discharge looks like. If it is white and cheesy like with no smell its probably yeast. Try an over-the-counter treatment for yeast infections. If that does not help seek medical advice.