I am in z:4 and have several brugmansia blooming in my unheated garage. When frost threatened in late September I dug them up and put them in 10" pots to spend the winter in a cool dark basement room. Since they had many buds I wanted to see them bloom so have waited to bring them inside. The blooms have been spectacular and lasted for a long time. But temps are falling and soon I will have to bring them inside.

One smaller plant was brought inside last week full of blooms. The blooms did not last long in the 70 degree house.

Many brugmansia seem to wait for cool autumn temps to bloom. One of mine has bloomed on and off during the summer as well.

Brugs are very heavy feeders, the re-potting probably helped. I don't know how often you fed it, but twice a week is a good start. I fertilize mine about 3 times a week. but, seeing that you are in zone 6, do not fert anymore till spring, and only since it's inside, even in a cool room, water sparingly, only enough to keep the root ball from completely drying out. It will drop its leaves and go simi-dormant till spring when it goes back outside.
Dan