Why is my iPhone 4 storage messed up & how can I fix it?

Hi. I have an iPhone 4 with the 6 GB of storage. The highest update I have on my phone is iOS6.1.2. Alright. Well starting this weekend, my phone informed me when I went to take a picture that I was out of memory, to check my settings, so I did so. I've deleted most of my apps & and deleted and reset my messages and calls. Well after deleting a couple of apps my megabytes went up some, but now every time I delete something so my memory isn't used up, it brings down my megabytes instead of bringing them up. My storage is completing screwed up and I can't download any apps and if I take a picture, it wastes my usage. I added up my usage and I should still have about 3 GB left. How can I fix my problem? My mom and my boyfriend both have iPhones with a lot more stuff and theirs is only using about 1 GB.

You can try to restore your iphone to original factory settings by plugging it in to your computer, going to itunes and select restore iphone.