64gb iPhone 6 says it's full. It's not.

Hi everyone! I've had no issues with my phone until this week.

A prompt suddenly came up and said i was running out of space, so i checked and had 1gb remaining-while crazy since I always have 20gb free, I did just go on vacation and took pictures- so I moved my pictures (about 2gb total) to my HDD and deleted those on my phone. Checked my memory usage and only had 0gb remaining. Did both a soft and hard reset and I jumped to 441mb remaining. I did that trick of manually jumping time to automatically remove the pictures from the recently deleted and still only had a few hundred megs.

I hooked up my phone to iTunes and that usage bar is less than half full (adds to about 25gb) but only registers 441mb remaining. Any ideas? I'm on 8.3 since last week but to be fair if this memory issue started then I hadn't noticed yet.

Any help would be appreciated I'm just afraid the only solution would be a factory reset. Thanks.