Although vaccinated children are known to shed virus a few days after vaccination, the vaccine virus that is shed is less able to spread from person to person than the natural infection. The amount of virus shed is normally below the levels needed to pass on infection (transmit) to others and the virus does not survive for long outside of the body. This is in contrast to natural flu infection, which spreads easily during the flu season.
It is more likely that you had naturally acquired flu and that you will hopefully have had less severe infection than if you were not vaccinated.