I used to have a baby (he's almost three now) that loved the left and hated the right. I hated the right too, it was hard to nurse him. Here's what I did, I hope you can picture it.
Hold her in the same position as you would the left. Use a boopy or pillows but have her body hanging off your body. So she is nursing in the same position as the left. I also had good success with the football hold.
I hope things get better for you.
Of all the words of mice and men, the saddest of these are might have been.