Let's talk about socks.

Finally edited. Thanks to tigermelp for the new clue #8. Should have a unique solution now.

I have six boxes, and 21 pairs of socks. I want to distribute the socks so that the first box holds one pair, the second box holds two pairs, etc. Given the clues below, how do I do it?

1. My socks are white, gray, brown and black.
2. I have more brown socks than white socks.
3. I have too many black socks, and can’t fit all of them into a single box. I can do that with any of my other colors, though.
4. I don’t want all of my white socks in the same box, but I don’t want any of the pairs to be alone, either. I need at least two pairs of white socks in any box that contains white socks.
5. There should be exactly one pair of gray socks in every box, except one.
6. All of the brown socks should go together, in the same box.
7. I want to get all of my black socks into three boxes.
8. Both of the socks in the second box are the same color.