i'm at exactly the same place you are, and i plan on going to day 80. day 65 right now and just starting to see any ambers on the buds themselves, even though the sugar leaves have a good dusting.
you've been budding for 15+ weeks? i'll be done by 12....something aint right in your room.you said you have a hps, what wattage is it and how high is it above your plants?
And 50% amber is a LOT, i like to pick at around 10%. the plants continue to mature for at least a week after you harvest, so by the time you dry and cure 10% could easily become 15 to 20%.....50% could become 65% or more