My no-poo/low-poo experience is that I didn't stop all at once but gradually went longer and longer washing my hair. I have tried suddenly stopping before and it was just horrendous. This past winter, I went from washing every other day to every third day for a month or so, then every fourth day, then every fifth day, etc. It takes time. Six weeks is a good trial, but it's not really that long in the grand scheme of things. My recommendation is that you try either:
1. Each month, extend the time between hair washings by one day.
2. Each month, dilute your shampoo by half or use half as much.
It'll probably take six months or maybe even longer to 'train' your head, but once it's used to it it'll just tick over as long as you don't wash it with shampoo and have to start over. I don't have the best hair ever, but if 1 is disgusting and 10 is freshly washed, mine settled at about an 8. I can deal with that. I don't use any product at all (if you're getting into all that vinegar faff you might as well just use shampoo) but I rinse it every few days (when I remember/can be bothered/get it wet anyway) in the shower. I don't blow dry my hair, which I think helps. I just towel it off a bit and then let it air dry (it's pixie-cut length so it doesn't take too long). It also helps to buy a bristle brush and brush your hair thoroughly every morning, both with your head up and bent over if it's a bit longer.
Not to get all TMI, but I was hoping that stopping using shampoo would stop my dandruff. It didn't, but then neither did any of the commercial anti-dandruff products so I'm in about the same boat as I was before. And it's certainly less hassle and less expensive than my shampoo-buying, hair-washing days.