The number of chunks is higher than that.
Firstly for file objects the data map is not stored directly in a mutable data anymore but a pointer to it is stored instead, so that creates at least one additional chunk (see MaidSafe Dev Update - February 23, 2017 - #72 by tfa).
Then one additional MD is created for each file of a safe site (see MaidSafe Dev Update - February 23, 2017 - #85 by tfa).