you've done all what you could, now it's too late for increasing the flower size, but you can focus about resin production: try turning the light off 2 days prior the harvest, flushing the LAST day with some cold water and some ice cubes ;)
splitting the stem a few days before also stress the plant and increase a bit the resin production, but I don't recommend it since it's very difficult and sometimes useless..
happy harvest!