Ive currently got some autoflowers on the go, on 6.5 weeks right now. They all still have at least half the hairs still white, with new hairs appearing each day. Checked the trichs yesterday just out of curiosity - expecting to see mainly clear with a few cloudy and no amber - and found more cloudy than clear and surprisingly one or two amber. Now all of the strains are supposed to be Indica dominent, but I was still surprised with what I found, when they are meant to have a lifespan of about 10 weeks. But then the evidence is there, the trichs are saying they're reaching their peak. This equally applies to you I would say - those trichs shouldn't be lying.
How do the flowers/buds look? What colour are the hairs? Mainly brown? Is it still throwing out new white hairs?
If they look good, with mainly brown hairs and few if any new white hairs - then I would suggest flushing, and keep an eye on the trichs. If the amount of amber starts to increase - chop asap. If it doesn't, and the plant keeps growing ok then let her go untill the amount of amber does start to increase and then chop asap.
Hope that helps - although of course, it is only one of many ways it could be dealt with.