Jesus dude, you went down to .0001. That's pretty great. And I cannot more highly recommend people get calibration weights to verify their scale, particularly when dialing in microgram levels. Having said that, there is no need to pay $100 for calibration weights. AWS has a set that includes 1mg, 2mg and 5mg, along with higher weights for around $15. I use them and find them to be incredibly accurate.