IPhone says no more storage but I only used up half?

My phone always says "out of storage" and even when it's not I only have a few hundred megabytes left. But today I added all the storage my phone says is taken up by my apps and it added up to just under half my storage! I should have 6 free gigabytes. What's the problem? Btw I included a picture below. Only thing it doesn't show is a few apps that in total equal 25.9mb IPhone says no more storage but I only used up half - 1

That list you show is incomplete. But you probaly want to connect to iTunes so you can see where the space is being used. My guess is there are photos in the "recently deleted" file, lots of iMessages, lots of voice mails in the deleted voice mails section… And that is just a start… But a good start.

There's 'other' taking your iPhone space, too. The 'other' is including apps' cache file. You can use some software to clean it. I use iMyfone Space Saver for iPhone. It can free up iPhone space by junk file clean-up and photo compression. Quite useful.