It needed to flower much longer. You harvested early. Don't even bother looking at trichomes until the plant is visually done. You're doing it backwards and looking at trichomes first and cutting early based on the trichomes. I like many others don't even look at trichomes. I don't need a microscope to know when the plant is done.
If you're going by that chart many go by then stop. It's a terrible chart that leads many growers to harvest much too early.
This is the chart I'm talking about. It's a terrible information. And what makes it so bad is that it's from a website that many apparently get all their other bad information from.