DD was a big baby at nearly 9lb at birth. She took to breastfeeding well and never went below her birth weight, putting on weight hand over fist from the start. Always alert and happy in the day.
However, she slept through the night for up to 7 hours at a stretch right from birth. When the midwife asked how many times she fed at night I told her never, she had always slept through. Cue much concern on her part as she tried to insist that I must wake her and feed her every 3 hours throughout the night as "she's probably too weak to cry!"
This was a baby putting on loads of weight and holding firmly to 95th centile who was as we spoke crying very loudly for a feed!
I ignored her. DD has somehow survived to adulthood.
OP, unless a baby is small, prem or has other health concerns you can rest assured that a baby will let you know in no uncertain terms if they are hungry! No way should you be waking a sleeping baby who is thriving and putting on a healthy amount of weight. Your baby seems to have got this sleeping business cracked and all this waking her at night could be setting up artificial sleep problems.
Let her sleep and thank your lucky stars that you have a healthy baby who sleeps! 
(note: this is no smug mummy boast, DS was a completely different story, he didn't sleep through for a year!
)