And rth 2.16ohms?

 

Your Vth is correct. Your Rth needs work. How did you get that value for Rth

 

Ok so its 9v

Okay, now all that's left is to determine the equivalent Thevenin resistance.

You seem to have gotten the parallel combination portion down.

All that's left to do is short the voltage source and find the equivalent resistance as seen by the terminals of the load.