First, thanks for the input! I really appreciate it and I'm feeling a little more mellow (mellow?...did I just age myself?).
I've been using the bottles the FM gave me because, of course, he doesn't care for the brand I bought. What I realized was that all of the nipples are #1 except one of them-which is a #2. The #2 was on a bottle that was set aside from the others and I hadn't been using it simply because it wasn't handy-not because it was a #2. I started thinking that maybe he is just having to work too damn hard on the #1s and gives up. Tonight, when I put him to bed, I grabbed that bottle. I didn't have a whole lot of hope because he had just finished 3.5ozs of formula and a half jar of squash 2 hours earlier. I didn't think he'd be hungry enough to prove anything to me either way, but I wanted to give it a shot. He slammed almost all of the 6ozs down in minutes and promptly fell asleep while probably thinking, "it's about time, fool". I'm excited to see how the next feedings go. Of course, now I have to find this brand...WalMart doesn't carry it. Off to check the Target site!