Things don't add up. If this is a test to see if you can get the desired intensity, then why run the LEDs at a fraction of the power? Is that 2mA per string, or for all strings combined?
Anyway, I stand by my earlier suggestion of using a dimmable led driver; it's the most straightforward approach. The datasheet of the selected part always has a formula for calculating the inductor needed for a particular use case.