How to increase power of a wireless power transmitter circuit?
As mentioned in a comment, 1N4007 diodes are useless at this frequency. All silicon diodes have what is known as "reverse recovery time". When a diode goes from forward conducting to reverse blocking there is a period of time that the diode will conduct during voltage reversal. A lot of diodes are sub 100ns but the 1N400x range is 30 us. Given that you are switching at 2 MHz and this has a period of 500 ns, the 1N400x will never work as a rectifier.

Also ensure that your secondary tuning capacitor is the correct value to make the secondary resonate.