Wisteria blooms on "old wood", the branches & twigs that have grown during the summer & autumn preceding the spring bloom season, so if you've pruned it at any time other than *immediately* after its bloom season (in the spring when other wisterias in your area lose their flowers), you've pruned off next year's flowers.

High nitrogen fertilizer promotes the growth of foliage but not flowers, so if your fert has a high first number (ie 15-2-2 or some such), it's the wrong kind.

I'd leave it alone, let it rest til next year, no pruning & no fert, & see what happens.

Best luck!