Well, perhaps you could recalibrate your upvote reflex toward making complimentary comments. :c)
Unfortunately 11 full-power upvotes seems to be the most that a user can deliver each day and retain a high %. I'm personally happy to manage to keep vote power above 80%.
While I am sure that this is not the case in your case - some do mistake the upvote button for a 'like'. Its a curation tool intended to help indicate which posts are more worthy of reading than others. Thus, the limitation is what it is and needs to be worked around until the next adjustment. /:c)
and some actually consciously do use the upvote button a like. I am pretty sure I didn't make 2 SP by curation. I mean the most I ever got on a post was like 0.003 ^^. So you see what I mean.
Well since you are at over 90% voting power as of writing it seems that you have voting power management down pat. :c) As to why you always get small rewards - its possible that the comments weren't as appreciated as you thought that they might be - or you could be voting a little too hastily - resulting in most of you curation rewards going back to author.