Q: Storage problem

Check your storage on your iPhone, iPad, and iPod touch - Apple Support

See above link

cam be a real pain you have no storage, getting that popup notification , cant take any pictures etc

SOLUTIONS

if you enable iCloud Photo Library in iCloud settings & choose optimise phone storage

THE PICTURES on your phone will upload to iCloud , be accessable to all your devices & free up storage on your phone

if you were to start deleting app , do so from settings> general> storage

if you delete any pictures, make sure you also empty the recently deleted photos album

an alternative

BAck up your phone to iTunes on a PCs / Mac , then restore the phone to factory settings

had the same issue with my wife's phone,

i imported all her pics onto the pic first,

then hen created backup > then restored,

free'd up about 3G

Did you try plugging it into iTunes or restarting it?

What I recommend is putting all of your photos on a pc then making a FTP server folder on the computer so that you can still access your photos from your phone when you have a internet connection.

Another thing I recommend is downloading this app it has the ability to clear your phones cache files and temporary files which are not useful.  I use the app and it cleaned like 4gb all together.

If you are using Whatsapp, you will find there was a problem with an update which caused users to experience problems with storage on their devices. They have release a fix, so make sure you have the latest version on your device. If you are experiencing a different issue, then you will need to check that, but you reported 1GB for Whatsapp in your original post.

You're welcome.