A 16GB iPhone is a disgrace to modern day technology. So fuck you Apple.
Having said that, if you have 1, you should get this app to sort your camera roll based on size so you can clean it up.
Also, get yourself Microsoft’s OneDrive to store all your camera roll on the cloud. That’s my setup. Photos go to OneDrive and then I delete them from the phone.
Photo Cleaner – Delete, compress photos & videos by Jinpyo Hong https://appsto.re/us/qpWm3.i