A flight

After leaving my baggage at the check-in desk, I went to/through security. After that (already used "After" in preceding sentence), In the terminal, I stopped to buy a gift in duty free. I got to the gate just in time, showed my passport and boarding card/pass, and then boarded the plane. (need to add comma)
There was no space left on the plane in the overhead lockers, but fortunately my hand baggage was small so I put it under the seat in front of memy. I sat down, (I) fastened my seat belt, and (I) watched the flight departed on time. I enjoyed the flight! (last sentence seems slightly out of place. Too quick of a temporal shift from the second-to-last sentence)