[IbnAlfreak]

Hello all, I searched the forums and couldn't really find if someone was having a similar issue. Ever since I bought this car last summer, the temperature would be just a hair above the center point. Over the winter, it's creeped up a little bit more than it was this summer. Occasionally it will get up to about where I drew a red mark on the picture. I changed and bled the coolant and it seemed to be okay for about 2 days and went right back to where it was.

When I turn on the heat the temperature goes down to normal and everything is okay. The heat seems really HOT though. I checked for the common symptoms of a bad head gasket (milky oil, smoke from tailpipe, loss of coolant) but haven't seen anything to make me concerned with that being the problem. I also checked to see if the fans came on, they did. I noticed the car runs pretty much at the half-way mark when I am driving on the interstate. My next guess is maybe the thermostat is stuck closed, could that be the issue? I let my car idle till it got up to temperature and checked the surge tank and there was no movement of coolant whatsoever.

To recap:
-Temperature above halfway and sometimes directly in between the 1/2 to 3/4 mark
-Seems to go to halfway mark when driving on the interstate and when heat is cranked up
-Heat is SUPER hot
-No movement of coolant in surge tank at operating temperature

If it is a stuck thermostat, what's the easiest way to get to it? Google and The Haynes Manual isn't too helpful on saying what to do.
I'm still new to all of this and am eager to learn the ropes. Thanks in advance for the help!