I've never seen a regulator that takes it's feedback from the input voltage!
I suspect R36 should go to ground instead of the input.
To get the voltages you need, find the values for the lowest voltage you want (7V) and a new value for the highest voltage (14V). Use a fixed resistor to set the lower limit and in series with it add a VR with value = the difference between low and high values. Adjusting it will then give a combined resistance of (fixedR + 0) to (fixedR + VR).
The formulas for calculating values are at the bottom of page 12 in the TI data sheet.
Brian.