are you sure that it has had plenty of food and water last year, if its leaves are very healthy I'd probably give it a high potash feed this year, if you already do this contact the nursery where bought and check with them-- maybe its a rogue plant

Make sure it is watered and fed in July/August and early Sept. This is budding up time for next years blooms. If you bought it where you usually go often, have a word with them about the plant too as suggested.