Breasfeeding to formula

Ok, so I was a breastfeeding momma. I fed the 2 year old until she was 6 months and we got preggo with her sister and the milk dried up (pretty funny way to figure out you're pregnant).  It's a good thing we wanted another baby and weren't using breastfeeding as birth control (it's not a reliable method, lol). I breastfed the baby until she was about 7 months old and I started drying up.

So, apparently not all formula is created equally.  They are all supposed to have about the same ingredients, right?  Not so much.  We used enfamil for 6 months with my older child and it worked well.  Should've kept to what works, huh. Noooooooo....someone told me to go with the cheaper stuff since it's all the same.  Diarrhea and explosive diapers 2x a day!!!! I should also add in that we tried to go witht the cheaper diapers as well.  If they all work about the same then it shouldn't matter, right?  WRONG again.  She exploded so many diapers we finally wound up returning the rest of the box (thanks to the 100% satisfaction guarantee) and the rest of the formula.  So far, since we've made the changes, we haven't had to throw out any more outfits.