Building a VCCS with AD8220 Instrumentation Amplifier
I'm going to suggest you abandon the approach you are taking because it looks like there will be too much of a learning curve. For a start you need a bipolar supply for a true AC delivery of current but I would just go for the Howland current source: -



The op-amp needs power rails of course and these should be typically bipolar in nature typically +/- 15 volts. Vin would be your voltage signal representative of a sine wave with no dc offset. Can be removed using an RC high pass filter.

You could buy one from Analog Devices if you didn't want to build it: -



It's good for well over 100 kHz.