Welcome fellow Texan. Your story follows a very common pattern, if you approach the scriptures logically and remove your cultural or denominational presuppositions about marriage, the conclusion you came to is the result. It is the only conclusion that can be argued without fallacies, reading between the lines, adding to the text or taking away from it, etc. It is simply impossible to teach monogamy-only as G-d's law from scripture alone.
I get a little heated now when I hear folks claim G-d simply turned a blind eye to "sin", rampant, flagrant, repeated, unrepentant sin (in their mind) over the course of lifetimes of these men and women... From both a logical perspective as that makes zero sense, and a spiritual one as it is speaking lowly of G-d and His righteousness and consistency.
Jacob physically wrestles with G-d, Abraham walks with Him, Moses speaks with Him face to face, but we are to believe He was just too pre-occupied with so many other sinful behaviors that He just allowed one as big as distorting marriage itself to slide by for thousands of years? Doesn't check out for me.