Give the battery some time. Also, if you really want to squeeze the battery out of it, consider just going with GSM. For me its ridicolously fast, I guess thats because of the signal reception in the N9 giving higher speeds on edge than the competitors.

I run it on edge all the time, and the battery lasts me a couple of days with a few hours of reading ebooks, few hours of music, and general use (calls, sms, twitter plus rss feeds on homescreen refreshed every 30 mins).

Email really screws the battery from what ive heard, i myself dont use email sync, preferring to sync manually.