Sorry, only just seen your reply. Will try to answer all your questions/suggestions....
At each feed I keep offering until he refuses any more milk point blank - if he drowns a bottle, i offer a few ounces more. I was slightly hoping that the NWs would just get later and later but they don't seem to - I've had a few where he's slept until 7am and was leaping around thinking we'd fixed it, only for them to creep back up on us.
We don't DF as such, in that he's awake for it but we do feed at 11.
He sleeps independently - for all his naps and sleeps, I put him in his cot awake and he sends himself off to sleep v well so am sure that's not the problem.
In all honesty, we've now got his routine sorted (he's been really unhappy on 3 and 3.5hr easy but finally seems v happy on the 4hr routine) and he's otherwise a very happy and easy little boy (a few weeks ago I thought he was a very tricky cus but now that the routine suits him, he's a different character). So really apart from his waking at 4am (which I'm almost 100% certain is habitual), and his crying in the lead up to bathtime (he loves actual bathtime but is just antsy at that time), he's the perfect baby so I can't really complain. Our daughter was v v v easy and slept through the night from about 6 or 7 weeks so he feels really late to me. That said, she's naturally got no appetite and is a slight build whereas he's a big chunky hungry boy!
Am a bit of a disbeliever in the W2S, cos I can't see how it could work, though I realise that some swear by it so perhaps that's worth trying. The only thing is that one night, we stayed up (with friends that had come around for supper) til about 2am and I fed him then instead of hte DF at 11 and he still woke at 5am, the naughty little sod, and yet was quite happy to sleep from 7pm til 2am when I woke him to feed. So we know he can do 7 hours at least.