While researching to answer this SO Question, stumbled upon this one, which gave me the final hint.
I'll reproduce the relevant part:
http://stats.wordpress.com/csv.php. If we visit this address, we get this response:
Error: api_key is a required parameter.
Required parameters: api_key, blog_id or blog_uri.
Optional parameters: table, post_id, end, days, limit, summarize.
api_key String A secret unique to your WordPress.com user account.
blog_id Integer The number that identifies your blog.
Find it in other stats URLs.
blog_uri String The full URL to the root directory of your blog.
Including the full path.
table String One of views, postviews, referrers, referrers_grouped,
searchterms, clicks, videoplays.
post_id Integer For use with postviews table.
end String The last day of the desired time frame.
Format is 'Y-m-d' (e.g. 2007-05-01)
and default is UTC date.
days Integer The length of the desired time frame.
Default is 30. "-1" means unlimited.
period String For use with views table and the 'days' parameter.
The desired time period grouping. 'week' or 'month'
Use 'days' as the number of results to return
(e.g. '&period=week&days=12' to return 12 weeks)
limit Integer The maximum number of records to return.
Default is 100. "-1" means unlimited.
If days is -1, limit is capped at 500.
summarize Flag If present, summarizes all matching records.
format String The format the data is returned in,
'csv', 'xml' or 'json'.
Default is 'csv'.
Non-working query example:
Result format is csv with one row per line and column names in first row.
Strings containing double quotes, commas, or "\n" are enclosed in double-quotes.
Double-qoutes in strings are escaped by inserting another double-quote.
Example: "pet food" recipe
Becomes: """pet food"" recipe"
Developers, please cache the results for at least 180 seconds.
For what I understood of this documentation, using
period=week&days=1&limit=-1' will return all posts from 1 week period. If we use
days=2 it will be a 2 weeks period.
One week seems to be the shortest period. You would have to compare Jetpack results with your internal query of only two days and filter the results.
Take that developers note seriously, as it looks I broke my daily (hopefully) quota while testing. The function is not returning results anymore and even preventing my code from running... Nothing breaks, but simply don't run.