Please help!- How to count and anlyze particle size

I am working on a project where I need to count and analyze area of small white spots on a green and black background. Each green tablet is set to a scale of 10mm which provides me with 70pixels/mm. The white spots I am trying to identify are extremely small. I am converting the image into 8 bit and then using the thresholding tool to identify spots, but I am having a problem not eliminating at least a portion of the white spots. This method also has a high error rate due to person to person variability.

Is there a way I can and measure the white spots with little variability?

Thank you for your help!

Below is a copy of the image in normal and with a black light to try and increase the brightness of the spot.