Moisture is the #1 enemy of bamboo flooring, although low humidity is not good for it, either. It may be that the floor was not allowed to acclimate to your apartment for the recommended week before being installed. In the winter, with drier air, the floor is shrinking and pulling apart, whereas in the more humid months, it swells and fits back together. You might consider two things; a humidifier in the space, and carefully painting the seams a dark color so that when they pull (and they will) it won't be as noticeable. If you still have your manufacturer information, you might also be able to get a rep out to make a recommendation if the floor is still under warranty.

Floating floors can be easily fixed, especially if no glue was used between the sections. You can replace only from the worst split to the closest wall, going the long way. And most of your current boards can be reused if they are not damaged. Of course you need to replace any sections that have been damaged, but only those. 1.) Call Lumber Liquidators and see if they still sell the floor in the right color, and of course check the warranty. 2.) See if they have a list of installers. 3.) When you put the new sections in, first find the same color in a furniture stain marker, and go down the sides of the new boards. If you have gaps that open up due to humidity changes, they won't be as visible. If you can, have the floor re-done in the winter, when the boards are at their smallest size, the expansion gap should be fine to ensure there is sufficient space for the summer expansion.

Your new installer may wish to use glue in that section in the hallway, to stabilize that high traffic area, when he lays in new boards.

You might check in with Consumer Affairs - Lumber Liquidators has been in the news recently for selling inferior products from China. I don't have the details, but your story rang a bell.