How do I find out where I purchased ETN way back during launch?

I’m not sure I am in the right section, but… I’m trying to reconcile EVERYTHING again for tax purposes. I’ve kept my original ETN in my ETN wallet since it was purchased, but never withdrew/traded it. This year I traded it and now need to reconcile the original transaction (which I can’t find).

I can only see the withdrawal transactions at my.electroneum. And, apparently my memory and documentation strategy sucks - because I cannot find out what I used to buy ETN. I know I used ETH, but that is about all I remember unfortunately.

When I look at my wallet on the blockchain, I only see the withdrawal as well - not how the ETN got to the wallet.

Any help would be GREATLY appreciated.