re: Question for those with a white 2000mah official extended battery
Had exactly the same issue - I also have the 9100P and the back cover is slightly changed from the 9100 , the tabs on it are deeper and the extended back will not fit correctly.
I have yet to find an extended battery designed for the 9100P , ebay , amazon etc all sell the standard one. . .
I have also found that the phone does not fit well in all cases - again the back appears to be very slightly deeper??
Sorry cant be more helpful. .
All the best