Hi, and welcome to the board! :)
Let me just say that I have no experience with going from BF to FF because I FF from the start, so I will answer all your formula related questions. :)
<<How do i know if she gets constipated vs. just less poop from formula?>>
Well FF babies can go up to a week without a BM and that is considered normal. If you see her pushing, going red, and crying, and nothing coming out I would assume possible constipation.
<<How do I prevent stomach problems for her? I have 3 different kinds of formula: Enfamil Gentlease (purple), Similiac Advance (blue) and Similac Isomil Advance Soy#(ed). Her dad is very lactose intolerant, no idea what she is.>>
Try and stick to 1 formula, trying all different kids will upset her tummy. I used similac advance and had no issues at all. Try with that maybe and if you see that it does not agree with her then talk to your ped and you may want to switch her.
<<What is the rule on switching to different kinds of formulas? Can I use the cans that I have and then go get a generic kind of which ever she likes best?>>
Like I said above, switching is not a good idea, I'd pick a brand and stick to it. Generic brands are the exact same as name brands.
<<Any other suggestions? I don't know anything about FF or how to do this.>>
In the beginning I recommend ready to feed because it's sterile and easier on their bellies. When she is tolerating formula well i would then stick to concentrate because again it is sterile and powdered formula is not. Also it's easier to make a mistake when mixing powdered formula than it is concentrate (concentrate is simply 1 can of formula to equal parts water). I would also recommend buying nursery water (sterile water especially for babies), it's cheap and easier than boiling the water and having to let it cool.
That's all I can think of for now, I hope this helps. Good luck and keep us posted! :)
