I'm with ya. "Probably" v lifelong kidney & thyroid problems...when there is a great alternative w/ no risk? Formulas are so advanced THESE DAYS you can feed them on demand... just like breastmilk. While I am a strong proponent of nursing/breastfeeding there are times when breastmilk is not only NOT best, but the worst available option. Like when on certain meds, or when your body simply doesn't have the available nutrients, or you've adopted, or there are allergies/ infections/ surgeries, or, or, or, or.
ALSO remember you owe NOBODY an explanation for how you choose to feed your child. You will probably tell some people/friends... but they don't have the right to approve/disapprove, & they don't have the right to access your medical records, etc. Icannot TELL you how many people butted into my life when this guernsey lost her milk at 9mo. Most of it was well meaning (have you tried...have you talked to...), but it was still -at best- an ignorant invasion into my privacy wanting me to 'prove' to them that a valid choice is a valid choice so they could relax and get the "Oh. Well for YOU, of course." response. I really am a huge proponent of breastmilk... but I'll tell ya what... I'm an even bigger supporter of assuming people aren't stupid :) Formula is a choice. And if someone is choosing formula... then I'm going to assume it's the BEST choice for that baby.
LOL and back onto a subject with a plethora of choices:
It's pay through the nose expensive, but I would start out with premixed formula of any kind. The texture is *completely* different than powdered (silky, almost luscious) and is far less prone to gas and stomach upset than powdered. Aka... a good way to transition. Although...fair warning... some babies can never tolerate powdered.
DO order free samples online (although they won't get here in time, it will help offset the cost once you find 'the one', and during the trial and error period unless you just get lucky with your first pick). All the big name formula companies offer that service, and many also send out 'checks' ($25 worth of $5 not-coupons...aka you can spend all or some of them... like $19 off of a $19 can one time, and $6 off another).
No matter WHICH brand ... there will be people whose babies thrived on it, and people whose babies were made super sick on it (gas, vomiting, constipation, etc.). So it's trial and error.
While there ARE minimum guidelines that are very strict, that does NOT mean formulas are all the same. In fact, quite the opposite; formula companies "niche" out. More broken down proteins... more complete proteins... whole food based nutrients/vitamins, broken down nutrients/vitamins...hypoallergenic....animal v plant v synthetic sources...etc.
For US... the *worst* were the ones with 'gentle' proteins (aka already partially digested/broken down (similac sensitive & nestle goodstart). Enfamil lipil premixed was the way to go (powdered created mad problems regardless of brand :P). For my niece; just the *opposite*; Similac is fantastic, enfamil gave her the projectile vomiting my son got on similac. Both needed premixed. My goddaughter THRIVES on powdered. Goober.
Trial & error.