Ofcourse you will have that high HPS with a disc priest in there which can't pull any compareable healing.
It's basicly like doing it alone and in that case it's a job well done by you for pulling it off, but the HPS aint impressive.
You should really consider having your priest either learning to play or speccing holy, having the paladin and you inside will give a better output - we use holy paladin, holy/disc priest and resto shaman (me), depending on what mood the priest is in he is either spec but it is surely doable as disc if you know how to play.
Oh and, you should not use lesser healing wave, waste of time