At this age, it's normal...they are still getting used to things and our world.
But, YOU can introduce regularity to her... instead of just waiting for HER to get tired.
Babies have this cycle of waking, then 2-3 hours after, getting tired again and needing to nap. At this age, even a diaper change or bath is an "activity."
Just put her down at the same times everyday. Some babies take very well to routine and regularity. This is what I did with my kids.
And now even at their ages, my kids still nap and go to bed fine.
I'm not talking sleep "training" or heavy-handed scheduling at this age... but regularity, and consistency. The baby will get used to it. It takes time.
By the time you actually see her getting tired, many times they are already OVER-tired...and over-tired babies or children actually do NOT sleep well... and they wake more. So this may be the problem.
They also need a pre-nap/bedtime "habit" so that they can unwind before napping.
Put her in the crib while she is still awake but tired... tuck her in etc., and let her sort of self-soothe and fall asleep on her own. Watch her, and see how she does. Many babies will make noise as they fall asleep and it's normal...but if she is then crying/screaming, then soothe her/help her.
Many times, swooping in right away at the every sound they make, just wakes them up and disrupts their natural falling-asleep process... so just try and wait a bit. Hang loose. And then she may fall asleep on her own. This is what I did with my son, and he is a great faller-asleeper now.
But go with what you think is appropriate.
But yes, I would put her down at regular times...
The book "Secrets of The Baby Whisperer- how to calm, connect, and communicate with your baby" is great. It offers great tips.
Yes, a baby needs to nap, even a child. Sleep aids in brain development and restoring the body.
And always feed on demand... if a baby is hungry, they can't sleep.
Good luck,
Susan