Do you feed your anemone? If not, start feeding it 2-3 times a week with a small portion of meaty food (a couple of krill, or 1/4-1/2" piece of fresh table shrimp). It should then begin to grow. IF it's a splitter, it will eventually split.
As for your clowns, it took my first GSM pairing 18 months together before they started spawning (second pair took 9 months), so if they are happy together, I wouldn't worry about it. Just keep them well fed with a variety of food and they will spawn eventually.
Kevin