Greetings youngfuture,
You didn't take too long.
IMHO here is what i believe happened to you--
By being in church you opened up to high spiritual energies, despite you don't go often. I believe your headaches were from those energies building in higher areas chakras. By being with your friend you were free to be enthusiastic, earnest, and free to feel your connections with those previous visits. --So all this perhaps established your intent, even unconsciously, that these were good places and that you wished to be there again.
Which leads to the bright flash of light----
When I've experienced that a couple or few times, it has turned out to be a confirmation of the future, a confirmation of a connection that perhaps you had even before you were blessed with your recent trip. IMO you will go to that church again and find connections to it that you perhaps you are not now aware of.
It also means of course that Spirit is working in your life, despite your not going to church frequently.
Enjoy the spiritual journey!
bets
I like that you felt blessed to have been able to visit these old cities. They have the energies of hundreds of years of souls meeting there, something some of us don't get to feel in the 'new' countries.