Hi,
I suggest the following:
To have a realistic thickness for your patch, feed line & gnd plane, consider 1 oz of copper (~1,4 mils or 0.034 mm approximately). These numbers depend upon what thickness do you specify to the PCB manufacturer while manufacturing this design. I usually use 1 oz of copper in my pcb designs.
I am not sure on this end, but you can make the ground spread out on the complete board dimension on the bottom layer. Currently I see you have it only below the feed line. Also I think you can consider the feed line as a microstrip and use any of the online microstrip calculators to decide upon the feed line's width to match the 50 ohm impedance of your patch.
I hope this helps to improve your design.