13 hours at night seems a smidge on the long side to me (at least from my personal experience with our kids). My oldest always went to bed for the night a little later than I read about others' doing, (around 9:00), so when we had #2, we "Ferberized" and started her going to bed around 7:30. 6:00 pm for bedtime for the night seems a bit on the early side. If you can work the schedule so that she goes down a little later for the night, then she will probably adjust her wake up time to a later time also. At 11 months old, she is growing into a little person, and leaving babyhood behind. Her sleep schedule will reflect that... only babies sleep so much (LOL). I would try moving back the bedtime by squeezing in a quick "doze" when she is crankiest (4:00 ?). If you have to, drive around the block a couple of times so that she falls asleep... only let her sleep for 20 minutes though. Then make her bedtime at 7:00pm. The next morning she may sleep a little later, if not, that's okay.. just try to hold off her morning nap a tiny bit (not until 9:30, 9:45?), then make sure she sleeps for a full nap when she does take it (if she is up in 10 mins, she isn't ready to be up yet). Let her play hard after she wakes and has lunch, then try to hold afternoon nap until 1:00 or 1:30. If she gets a full morning nap and afternoon nap, she should begin to last until 7:00 pm for bedtime. Then 12 hours at night is pretty "average" I think. My kids NEVER slept past about 7:30, and often were up by 6:30 or 6:45. But their standard bedtime (when the oldest was 3 yrs and the baby was a baby) was 7:30 for the oldest and 7:00 for the baby. By the time the baby was 3 yrs, they were going to bed at the same time... around 7:45 pm, and cutting out every nap they could manage to avoid!
I would try to approach it with the idea of changing time zones... Because it sounds like you really just want her to go to bed a little later and sleep a little later the next day...