My son got ear infections while exclusively breastfeed - multiple ones. Once I isolated him from some sickly children he was around he stopped getting them. He would get their colds and then get an ear infection. That was from about four months old to eight months old.
My doctor said that when the child is nursing it's easier for them to get fluid up into their ear (from their nose or throat)*. You can help this some by changing their position to be more upright when nursing. My little touchy guy liked to nurse one way - lying down in the clutch hold - and lying perfectly horizontal. That was part of the problem. Letting my little guy sleep in his c!@!@at also kept his head upright and allowed fluid to drain rather than gather in the ear. Of course, by eight months he was too old to sleep in his c!@!@at so I tried elevating the crib and keeping him upright as much as possible during his awake times.
At one point, when he was closer to eight months old, my son's pediatrician prescribed a nasal spray that was not just saline. It was either a decongestant or antihistamine spray. I had to use it for two grueling weeks, twice a day, too help dry up the fluid. It worked like a charm so all the fighting with my son was worth it. He didn't have another ear infection for months and even now the way to avoid them when he gets a cold from all the other kids we're around is to give him decongestant and antihistamine until the cold is gone. The fluid never gets a chance to build up that way. Has your doctor suggested something along these lines before trying the tubes?
*This is also true for babies fed from bottles, which is why they advise keeping the child at a 45 degree angle - not lying down, or partially lying down - while feeding them from the bottle.
