okay, i see. but how do i extract the nmea information of this and put it on a string?
It would be very helpful if you got someone else to type your responses here in the forum, and you put your hands in your pockets. All the handwaving that you are doing is completely useless.
Why does sendData() read anything? There is NOTHING in the name of the function that suggests that it should do that.
You send a shitload of AT commands. I could guess, but I am not going to, that some of them tell the GPRS shield to send back GPS data. You need to figure out which one of the AT commands does that.
YOU then need to get the data that is sent back in response to that command and store it in a string.
YOU then need to parse that string to get lat and lon data.
Keep in mind that serial data is asynchronous, so what data is available NOW to read may be in response to some command send 12 commands back, NOT the last command sent. The data available to read NOW is only in response to the last command sent if you break the asynchronous model, by waiting for a response, and KNOWING when a response is complete.