Iphone4 storage

I keep having a message that I cannot take photos because storage is full. When i looked, it says I was using 5gig in my messages. I deleted all of them but only got back 200meg....??? I am not understanding this. I just deleted my safari history, got an 80meg back...If I delete photos from my iphone, it is not giving me back space either....****** windows 10 wont recognize my phone when connected and my mac wont sync because itunes needs a newer version (but it's updated). Any solutions?