Many factors can be attributed to low yields, like you said nutes and watering, but cold can also be a big issue.
Also, dropping your light to 10 on and 14 off will help simulate a shortening day just like nature would start slowing down to bring on the bud production. So, if you were to drop the time it may help the girls finish up, although, keep in mind if you are relying on lights on to produce heat you may want to rethink it and let them be They are looking nice and green, enjoying your xmas tree that is awesome!!
Also, dropping your light to 10 on and 14 off will help simulate a shortening day just like nature would start slowing down to bring on the bud production. So, if you were to drop the time it may help the girls finish up, although, keep in mind if you are relying on lights on to produce heat you may want to rethink it and let them be They are looking nice and green, enjoying your xmas tree that is awesome!!