Hi hillbilly - I don't have much time to spare but here's my brief thoughts:
He might need the milk - if feeding helps him go back to sleep, roll with it! NCSS is really good but don't expect rapid results and at 15 weeks it's still really really early to 'train' them, IMO. You are approaching a classic 'bad sleep' stage (most people seem to arrive in here at 4 months, it seems, and the gang who originally started it had 4 month old babies too ). There's a good article on sleep regressions on 'Ask Moxie' (a blog, can't link you to it right now but someone will I'm sure).
Basically, my advice is do whatever it takes to get yourself and your baby to sleep and forget about the rest. Bad habits can be changed later, but my experience is that they change and grow out of things so fast there's no point stressing about it because they drop their preferred habits randomly anyway.
I have a nearly 7 month old and I remember your stage like yesterday (possibly because I've been awake since them, or so it feels!) but things are loads easier if you can go with the flow. Have you considered co-sleeping? It really helps a lot of people through this stage. I still cosleep for much of the night = otherwise I'd get no rest at all.
Hi to all the regs, well done on successes (Meg!) and hope everyone is well. No time just now (work ) and V V V tired but hanging on in there .
Brief?