Doctors are always trying to cover their own ass. I'm a nurse, I should know
It is alot easier for him to walk into the room, tell you to wean, and then walk out with no thoughts about how it is going to effect you and your daughters life than to look up the drug online or in a book.
You've gotten great resources here on this forum : )
Do what feels right to you and don't worry about going against what your doctor says so much. Your pediatrician said its ok and people who actually care enough to look it up say its ok. A lot of times the risks associated with using formula are worse than the small amount of drug you are taking getting passed to baby.