Nina is just over 5 months and used to go to bed at 6pm as well, now, like you, it's a little harder and she doesn't normally go to bed till around 7.30, after some rocking though. She too is having a nap at around 3.30/4pm, which as much as I try to stop, she's just too tired and needs it. Maybe it's just at this age they're trying to figure out what they want ... I dunno??