Outlook Calendar synch but ONLY have the past 1Yr appointments

Ok got this really annoying bug here:

I've always sync'ed the COMPLETE calendar from my outlook to my iPhone but recently I noticed that on iPhone it only kept my calendar from Jan 2012. (roughly one year) Having said that, in my iTunes i did NOT tick 'do not sync events oler than 'x' days' and chose sync ALL calendars.

Yet this is still happening. I know I can select Calendar on Advance so that it will replace the calendar on the iPhone w/ information from my outlook but it takes FOREVER. More importantly I want to know why this happened repeatedly and more importantly how to prevent this from happening again?

I first noticed this a week ago so I bit the bullet and "replace calendar information on the iPhone w/ data from PC's outlook" and that took HOURS.

I have iP5 w/ 64Gb and outlook 2010 on Win7. Any hint please.