Do we know for sure he consummated it? (I'm not doubting you, I am just curious to know how to verify this)
Yes...and he was already married to her for three years.
Sahih Muslim Book 008, Number 3310:
'A'isha (Allah be pleased with her) reported: Allah's Apostle (may peace be upon him) married me when I was six years old, and I was admitted to his house when I was nine years old.
Sahih Bukhari Volume 7, Book 62, Number 64
Narrated 'Aisha:
that the Prophet married her when she was six years old and he consummated his marriage when she was nine years old, and then she remained with him for nine years (i.e., till his death).