I don't know about official requirements, but being a European En Route ATC I know for sure that we want:
- Callsign
- Flight level (maintaining, or climbing to / descending to)
- Any direct Route
So you were perfectly right.
The report position is not really useful, since 99% of the time we have radar identified you before your call. Although sometimes we're kind of "behind traffic" and may ask you "say position?"
