There is no question that this didn't happen in 2010. I've read all the controversy over seed words, BIP39 blah blah blah blah. Honestly forget that rubbish it's totally irrelevant in this particular instance...I was there in 2010. "Mnemonic" & "recovery phrase" is about the only possible terms used at the time. For those if you still debating how it was or how it wasnt it was originally EXACTLY how I have described it.
The human brain can play tricks on us sometimes, especially when it comes to memories from a decade ago. How can you be absolutely sure that it happened EXACTLY as you described when you yourself admit that you can't remember some key details? It's possible that your recollection of events is slightly off. For example, it would help a lot if you knew exactly which software you used to create your Bitcoin wallet or which website you used to buy coins. Do you have any concrete evidence (other than your memory) to corroborate any part of your story? What if it wasn't Bitcoin at all?