A 3d carousel is not a common interaction on a 2d screen, and it will have difficulties scaling up to show more curved photos.
The only options are to change the diameter/radius to accommodate more photos and/or make the photos smaller.
However, you might want to rethink using a 3D curved carousel due to the complexities involved in showing more photos.
My advice - keep the carousel simple and your users will thank you for it.
Also a more simple carousel interaction will be quicker, easier and cheaper to code and test.