well this is how it usually goes:
5am wake up for feed
8-9am wake up for feed
1.5-2hrs later have a nap for around 2-3hrs
awake for 1.5-2hrs then another nap for about 2hrs
once she wakes up after that second nap I have no hope of getting her down no matter how hard I try!! So I don't think she is over tired cause I don't keep her up longer than 2hrs...

I wrap her and put her down even if she is still awake for those 2 other naps and she usually puts herself to sleep.. but after she wakes in the afternoon she will not settle herself and won't go down after being rocked etc.