I guess the first question is: why do you care if what you are doing is in some sense end to end encryption? End to end encryption has a reputation of being hard to use as it normally has an identity verification requirement. Why would you want that association?

It appears that there is only one "end" here. So I don't see that there is any reason to make some sort of distinction between what you are doing and just straightforward and secure encryption.

What you are doing sounds more like this:

* https://en.wikipedia.org/wiki/Client-side_encryption