Here is Young’s Literal Translation of the Bible and a link for more research in the even that any Catholics are willing to take an honest, thinking outside the box, look at the Greek.
It’s clear that you are correct that Peter was affirming heaven’s decisions.
http://biblehub.com/matthew/16-19.htm
and I will give to thee the keys of the reign of the heavens, and whatever thou mayest bind upon the earth shall be having been bound in the heavens, and whatever thou mayest loose upon the earth shall be having been loosed in the heavens.’
Since Peter was affirming heaven’s decision then it follows that the whole basis for the notion of papal infallibility is, in fact, false.