The problem is, IO needs to count days you were in and outside of the US. Frequent trips may make you ineligible for N-400 if you spent too much time outside of the US.
A good advice for anybody getting GC in the future is to start a spreadsheet on Google Sheets, noting every single trip taken since becoming LPR.
Now, since you're in this situation, you may review:
- Bank statements (see charges in stores, restaurants, gas stations etc overseas)
- Emails (if you had hotel reservations, airfare, something else related to trip)
- Google Maps (if you have location history enabled)
- Chats (SMS, messengers) where you talked to somebody while being overseas
Good luck !