What does the little circle mean on my Sprint IPhone 5?

For the past few days I've had a little tiny circle in the top left hand corner of my IPhone 5 instead of the 3G. My phones been slow, doesn't connect to the internet and doesn't refresh. It's really bothering me. I've turned the IPhone off & on & that didn't help. I've tried connecting to WiFi, going into my settings to fix it but nothing seems to work.

That means you are using GPRS which is 1G, which will explain the internet speed being slow & sometimes not working.

You could contact Sprint about it since that is on them & their data network.