From birth Ewan has liked the left side best. Recently it has become even more apparent.
I've heard that babies can prefer one side over the other due to how their necks were positioned in the womb. They can feel more comfortable on a certain side.
Also, another reason Ewan might prefer the left side is that the right side was painful for me for the first few weeks. I'm pretty sure I had what is called a "Linear Inversion" on part of my right nipple.
A Linear Inversion is when a line of cells on the nipple is inverted but the nipple looks normal if you don't know what to look for. It causes sharp pain for the first few seconds of a feed and then stops. It mysteriously goes away after a few weeks.
I had this issue but pushed through it. During Ewan's second day of life I fed him more from the left to avoid the pain on the right. After that I would cringe every time I put him on the right and I could see him tense up too, reacting to my tension. Then we would both relax after the pain subsided. This only lasted for the first 2 weeks or so, then it stopped completely. Apparently it's very common.
Could this slightly negative experience on the right side have caused him to favor the left? Not sure.
Recently, he has been squirming away from the right side when the milk slows down. He is usually content to hang out in the left side cuddling and sucking himself to sleep, but rarely does he do that on the right. I have to switch him back to the left sometimes to get him to go to sleep.
I am not sure what caused him to favor the left side, but it is obvious to me that he does.