What usually happens w/ that darn 45min nap is because they only had 45min of sleep, they can only stay awake 1.5hrs (or a short time) and because they have only been up a short time, they only need 45min of sleep!
But if you lo is happy and you are happy, then do what works for your family.
That being said...If it were me, I would keep extending the nap. It will get better, I promise. It is very normal for infants to jolt from one sleep cycle to another. Extending now will save you from having to break a well ingrained habit later on. As 45min will not hold her over and still have her be happy when she is older and can stay awake 2.5-3.0 hrs.
Good luck! Hope that helps