Totally agree with what others have said. We had a little night-owl too. I think by about 3 months she was fairly consistently going down at about 10 so then I gradually moved it back 10 mins every few days.
The other thing that may help - and you're prob already doing- is less stimulation in that last wakeful period. Low lights, avoiding flickering light or too much noise from TV etc.

You sound like you're doing a wonderful job. Bub will find her own rhythm and in the meanwhile will benefit so much from having such a gentle, responsive Mummy around, even at 11pm!!