I think we may have FINALLY solved our bathroom leak problem!
We noticed the other day that the leak coming from the master bath was getting bigger, so as of last Friday we stopped using our shower and started using William's shower. I thought it was going to be a big pain, but it turns out that William actually likes to play in his crib in the morning instead of immediately getting up, allowing me time to take a quick shower.
I called our insurance company yesterday, and they immediately had yet another plumber (the 3rd one!) come out bright and early this morning. After cutting a rather large hole in the ceiling and removing the insulation, they were able to find a substantial leak coming from one of the pipes. They told me the builder "cheaped out" on the pipe, because there were no threads on the pipe - it was just threaded on the bottom of the pipe, and the top was just placed there. (Did that make any sense?) Fortunately for us the pipe never ripped off, causing an even bigger problem, but we still have had to deal with this leak for quite some time.
Now we're just waiting for things to dry up before we get a handyman over to repair the hole in the ceiling. I'm SO excited that this problem is solved!!
(The leak was just above the orange part in the pipe.)