Elterngeld (for permanent Teilzeit) (Munich)

Hello,
I have already read several links about this, specifically for doing part time during the Elternzeit (should be less than 30hrs per week).
But I have always worked Teilzeit (25hrs per week). Does anybody know if I would get the complete Elterngeld if I go back to work early? (Before the 1yr. parental leave is done). Because technically I am not losing income for decreasing my work hours, and the Elterngeld is computed on this "lost income", if you work Teilzeit during the Elternzeit.
Any help would be greatly appreciated.

Br,
Janice