My daughter just barely started STTN and sometimes that doesn't work. The only way I got her to do it was by putting her in the crib. I just had to do it. I never let her CIO. I stayed with her and comforted her until she fell asleep. Now I can put her in the crib and walk away. She goes to sleep on her own. For a long time she would wake up around 3:30, so I'd bring her in bed. She would then nurse every 1-2 hours, thus driving me mildly insane because I have to work until 1 or 2 am, generally. I didn't do anything to get her to sleep longer. She just started doing it. I pray I'm not cursing myself now.
I really needed to do a gentle night wean to be able to continue our nursing relationship. The no sleep for the past 3 years was beating me down. You aren't alone. I don't know if I really considered her night "weaned," but I guess she is since she hasn't gotten up to nurse like that in a little bit. It's really only been a few weeks.
Hang in there.