Corner loading/left louder ?

Try toeing the right speaker outward a bit, and following listening to this experiment toeing the left speaker inward a bit (if needed) to further achieve L/R balance.

I’m talking tiny adjustments of the right speaker (like 1/2 inch to start) and then even more minute adjustments to the left speaker.

It may take many tries to achieve a decent channel balance (it’s a balancing act ruled by the room and it’s furnishings). 

I have an “L” or a “U” shaped listening room (take your pick, but I consider it a lopsided “U”) and have been able to balance various speakers over the years using this approach.

My speakers are approx. 10-13 feet from the seated listening position, with the right speaker being distanced the furthest

DeKay

you can create a system with a photo, description, and diagram as a jpg on here

set so everyone can see it and then point people to it

I am about nine feet from the speakers,, I sit center of them. 
They are about 7-8 feet apart

A lot of good advice, so far.
-Ghosthouse's advice of using a folding panel might be a way to reflect sound.
-Dekay's advice of using small adjustments to speaker position should also help.
Since you already notice an improvement from using 3 pillows, I think the advice erik-squires probably will probably give you the best result.

As far as 'more juice to the left', that isn't so. It is simply that you have one side reflecting more sound to your ears than the other side. 'Power' isn't a factor, just acoustics.
As I said before, if you can adjust balance, give it a try. Or, try moving the speakers incrementally.
If you want to nip the problem in the bud, then I believe going with acoustic treatments will provide you with the most effective means of resolving the problem.
Like most folk with high performance stereos, we don't have the ability to own a home with a room with perfect sound properties, so we have to either accept the deficiencies or try to compensate for them as best we can.
HTH 
Bob