If you know the month and year, that is normally good enough unless your trips are so many or so long that they push the limits of physical presence or continuous residence.
For the 2009 trip, surely you have some emails or something else with your itinerary where you can find the exact dates?
EB3 ROW I-485 Approved: July 2007
USC: July 2013
I am a layman, not a lawyer. What I write here is not official or professional legal advice. In addition, my answers on this forum are specific to the scenarios discussed in each thread and should not be generalized to other situations.