What kind of NPK ratio does the fertilizer have? It's possible the N (the first number) is too high, which promotes foliage growth but doesn't help/can prevent blooming.
I would also wonder if there is insufficient sunlight, but if the buds are forming that may not be the case. However, most blooming plants need sull sun (6 hrs) and even shade bloomers at least 4 hrs of direct sun or longer duration of dappled sun, but a porch is probably blocked by solid shadow of the house. Days are getting shorter now, which means depending on the direction the porch faces, it may be getting less sun.
Has it been very hot there? It could also be a form of blossom drop.
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