buyonsale the expected interior moisture content of your floors in your area is 6% mid winter and 7% mid summer, not considering HVAC effects. If your house's relative humidity is at 50%, and temperature 64 degrees F, your floors should be at 9.3% moisture content.

Your readings of 6% would mean that your relative humidity value should be 28% at 64 degrees F. Leaving more room for expansion won't help in the middle of the rooms. Give your wood more time to acclimate. Some times is takes much longer than 3 weeks. Chances are the wood was stored in sub 30 degree F warehouse and the moisture content of the wood could have gone down to 1%.