Do I need to wait 3 months after a long trip before applying for citizenship?

It depends - did you maintain a residence in the U.S., as well as other indicia of residence in the U.S. ? If so, then you probably can - but much more information is needed. You should consult with an immigration attorney as your lengthy trips abroad may impact your eligibility at this time.

If you moved residence in the last 3 months then you should wait.

More information is needed to properly answer the question. Did you maintain a residence in the United States while abroad? Were you outside the United States for more than six months?

The 3 month residency in the state before filing is judged by your permanent residency location during the immediate past. You need to be resident in the state for 90 days prior to application.

Really it depends whether you maintained your residency in the district where you will be applying. If, for example you gave up your lease, and then returned to a completely new area, then you will have to wait three months before you are eligible.