This may seem like a silly question, but I'm a first-time-mom-to-be, so feeding an infant is all new to me! I plan on breastfeeding, but I'm thinking ahead to when I'll need to pump and bottlefeed, when I go back to work, and I'm doing my "bottle research" now. I really like the convenience that the Playtex Disposable Nurser System seems to have, but I would also like to try a nipple that is more like the breast, to avoid nipple confusion (I like the sound of the Second Nature nipples and the First Years Breastflow nipples). Are most bottles and nipples interchangable or do you pretty much need to stick with the same brand for each? Thanks for the help!