Some strains never get amber trichomes, no matter how long you wait and some strains have 70% amber after only 4 weeks of flowering........it all comes down to genetics.
If your plants have 98-99% brown pistils/hairs, you are in the harvest zone.
Amber/brown trichomes are full of degraded THC that has been converted to CBD and CBN, giving you buds that can make you sleepy rather than high.
If you want maximum THC, 70 cloudy and 30 clear is about ideal.
More light, not less light will cause the THC to degrade into CBD and CBN faster and give you amber trichomes if that is what you really want, but at 14 weeks and without any pictures, I would say harvest now anyway, another few days is not going to make your buds any more potent, just more couch locking.