Have you been feeding it? I would start feeding now and perhaps once an month with Sulphate of Potash only up to the end of September.

we had a pittosporum yaers ago and the flowers were small and dark maroon and they were easy to miss. perhaps it has flowered and you haven't noticed.

welcome to GoY too :o)

Just had a look at your plant type and the flowers are white so shouldn't be difficult to miss. Perhaps it needs a good feed.

Also, don't prune after midsummer, since late summer is when the flower buds form. If it is actually one of the newer clones of 'Wheeler's Dwarf', these rarely bloom.