@Tapshi
Suggest you look at the limiting codes for each flap setting. You will find your take-off is limited by different criteria for different flap settings.
For Flaps 1 and 5 it is most likely field/obstacle limits
For flaps 15/25 you are most likely climb limited - although there may be an improved climb using higher V2.
Flaps 10 is probably close to where this changeover occurs