this is a good question. you got the order flipped. no amari talks about the thing thats in excess. right now, you are trying to pair something with “pain”. these points both indicate extent, but in different ways.
what the correct answer using of no amari, the sentence means something like “there was such an excess of pain, that i screamed”. this makes sense, as a large amount of pain would make you scream. i feel like no amari typically pairs with the cause. amari shows excess, its like due to the excess of pain, i shouted
putting kurai/gurai there wouldnt make much sense. it typically pairs with the result. if the sentence was something like 苦しすぎて、大きな声を出してしまう______痛かった。then something like gurai/kurai would make more sense. it shows how strong the cause (苦しすぎて) is by what it results in you doing (大きな声を出してしまうくらい痛かった). a literal translation would be “it hurt very bad, to the point where i shouted”
your using gurai in the original sentence is like “to the point where it hurt, i shouted” or something like that (i think, im not confident in this translation). but its weird
Thank you! It seems you’re right. I got a review with the cause and effect switched from this one, so I put kurai, and I was right this time.