And every thing I've read 'about' Greek in English says that Petros is a small rock; about the size of a basketball, or maybe even as large as an automobile...
Petra, on the other hand, according to everything I've read is a Rock...A Rock large enough you could land a 747 on it...
So it looks like that to justify 'upon this rock' I will build my church, and give it to Peter, you have to annihilate the greek meanings of Petros/Petra, which you appear to have done according to everything I've read on it...
Thus, the typical explanation about Petros/petra being two different things is specious, because that would make the text say: "you are a pebble and upon this same Rock I will build my church".
Like I said, everything I've ever read about it, not once did anyone else say it was specious...What they do say is that if Matthew was written in Aramic, they could justify what you suggest...Unfortunately, no one has ever found a Matthew manuscript written in Aramic...
On the Petros/Petra difference. Yes, you were taught a fairly common exegesis of that passage which attempts to distinguish between the meanings of petros and petra. I am by no means a Greek expert, but I do not think that distinction applied in Greek of the first century, though it *may* have earlier in Attic Greek. I will look it up in my Liddell-Scott lexicon when I get home, and I'm pinging jrny whose Greek is better than mine.
But even if that were so, that distinction does not seem to be what Christ was intending here. You mention the Aramaic Gospel of Matthew. We have evidence from the 2nd century that states that Matthew wrote in Aramaic (or Hebrew), but obviously that kind of statement is not infallible. What is infallible, however, is the Bible itself, which repeatedly calls Peter Cephas--the Aramaic form. Furthermore, John 1:42 shows which was the original form when it says "Cephas which, translated, is Peter." If Christ originally used Greek, what the Bible would have said was the reverse.
There is an easy explanation, moreover, why there are two different forms of "petr-" here. Matthew wanted to imitate the Aramaic in Greek: so he wanted to play on the word "Rock". However, in doing so, he was constrained to change the gender of feminine "petra" to make it fit a man: "Petros".
This is the explanation that best fits the available evidence and does not twist an interpretation out of the text which is not there.