I am using the smallest tube. I've only used this tube. She has recently been fussing less. I am now trying (maybe you want to try) not to release anything from the SNS until about 30 seconds from when she latches on. This way she doesn't get the instant flow. I think this may help with the SNS dependency. She started solids so she was having frequent stools that were hard little balls (I think she was constipated) until yesterday where she had a big breast milk diaper mixed with the avocado and banana I've been giving her. I hope that helps.
I've also been wanting to tell you that it's still really great that you are feeding your LO at breast even if it's with an SNS or a Lactaid. I'm routing for you!