Hi
I have come on here for the answer to the exact same question!!
Evie has always slept alot but her sleeping pattern doesn't really seemed to have changed and I thought as she got older she should be awake more!! She too is 5.5 months, she wakes at 7ish, back to sleep at 8.30, awake at 10.30 back to sleep at 12, awake at 2 and the afternoons I try to keep her awake longer and just let her nap so that she can stay awake until bedtime at 6.30-6.45pm!
We have just started weaning so I have dropped the 10pm feed so she goes down at 6.30 and we wake her at 7am!!
I guess we should cherish it while it lasts!!
Nicky