Transitioning from two naps to one

My daughter, the worlds best napper, has just lost her "worlds best" title.  She will be 18 months old in two days.  I think she is transitioning from two naps to one nap a day.   As I type this, she is in her bedroom, fussing and refusing to nap.  Her traditional first nap is at 10:30 but for the last two days she has protested it.  So, today I am trying a different tactic - I waited until she started to get still and cuddly then I decided she was ready for her nap.  We went to her bedroom at 11:00.  I read to her (always do this before nap or bedtime) then I nursed her (I usually only do this before bedtime.)  I nursed her hoping it would help calm her.  When I laid her down she fussed less than she did the past two days.  But now it is 11:48 and she just cranked it up loud.  Oh no.  This is not fun.  The stress.  I hate this part of being a mommy.  But, I love just about everything else.

Update:  After 45 minutes of talking, fussing, then loud crying she got quiet.  Asleep at last!  Whew, that was rough for us both.