I certainly don't know all there is to know.
[I'll just wait here a little bit while the shock of that statement washes over you.]
There are a couple misconceptions about heaven I've heard recently that I'd like to clear up.
When we die, we do not become angels.
Angels are a separate category of created beings, not the souls of our dearly departed relatives. So...sorry...Uncle Billy is not your guardian angel and the attempt to comfort the grieving by saying "I guess God needed another angel, so He chose Uncle Billy" is just wrong-headed. Right-hearted, but wrong-headed. (In the same breath, I might as well burst the bubbles of those who think we all live in heaven until we are born.)
The main attraction in heaven will not be seeing all our loved ones who died before we did.
The big deal in heaven will be worshiping Jesus; seeing Him face-to-face. Do you really think we'll prefer sitting around talking to Uncle Billy over knowing Jesus fully, just as He fully knows us now? (I Corinthians 13:12)
Truth is...I could have titled this "Stuff We KNOW About Heaven" and left the page blank.