Yeah, those are common concerns about the Book of Mormon that I've heard a lot over the years. But I'm not here to argue, and I'm still a learning work-in-progress (aren't we all?), so maybe I'll eventually arrive at the same conclusions that you have. We'll see.

It's important to understand, though, that the Book of Mormon does not teach another gospel; it confirms and testifies of the gospel that's taught in the Bible. As Paul also said: "In the mouth of two or three witnesses shall every word be established." (2 Corinthians 13:1)

Also, Revelation 22:18-19 is only referring to the Book of Revelation, not the entire Holy Library (which is what "Bible" means). The Bible was not written all at once, or in the order that the books are in today. And most scholars agree that the Gospel According to John was written after John wrote the vision that became the Book of Revelation. So if it applied to everything written after that point, then we shouldn't include the Gospel According to John in the Bible.

If we choose to apply those words to all the currently-available words of God, then we must also follow the words in Deuteronomy 4:2: "Ye shall not add unto the word which I command you, neither shall ye diminish ought from it, that ye may keep the commandments of the Lord your God which I command you." That would mean that everything from Joshua to Revelation would not be God's word. 

Of course I don't believe that; Deuteronomy 4:2 only applied to the Book of Deuteronomy. But the point is this: Is God incapable of adding more to His words? We know from the Bible that 10 of the tribes of Israel were lost, so is it out of the question that God would have spoken to them, too, and they might have written down His words, as a testimony of Jesus Christ and the words He gave us in the Bible?

Sadly, the LDS church has done a 𝘭𝘰𝘵 to give people the wrong impression about the Book of Mormon, all in an effort to puff itself up as "the one and only true church." The purpose of the Bible is to point the reader to Jesus Christ; the purpose of the Book of Mormon is to point the reader to also read the Bible 𝘢𝘯𝘥 to point them to Jesus Christ. So if you choose not to read it, but you've already found Jesus (which it seems like you have), then it might be unnecessary for you to read it, anyway. For me, I choose to look for truth wherever I can find it, so of course I started with the Bible, but God confirmed to me personally that truth is also found in the Book of Mormon, and also in many other records from other lost tribes of Israel that haven't been discovered yet.

Thank you for your kind words! I really hope that what I said didn't sound harsh or argumentative. That's the last thing I want! We're both on a journey to Jesus; any disagreement over details along the Way is, as Jesus would say, "strain[ing] at a gnat, and swallow[ing] a camel." (Matthew 23:24)

So I'll prayerfully consider what you shared with me, and trust God to lead both of us wherever He needs us to be. I believe you'll do the same. 💜