Cindy, so, it's still the temperature doing the trick
After tried growing mine under full sun for a year with very slow in growth, I decided to changed it's growing condition (after getting some advice from you).
I can't put it in my room with aircond as my window don't get good sun light. Now I put it in my garden for 2 to 3 hours morning sun, bright for the rest of the day, the biggest pitchers recorded 1 cm in length. The temperature is 24-25°C average at night. I'll see how big the pitcher will go.
Jamie, live sphagnum moss grow well under direct sun if provided wet / humid condition. Try growing it with long fibre sphagnum in an undrained container (without any holes at the bottom), but drill a hole or two at the side (about 2/3 the height of the container from the bottom) to allow access water to flow out, so the live sphagnum moss on top will be always just d-a-m-p. Mine growing very well with this method, I have two pots growing vigorously in higher pots (with holes at the bottom), but I water twice a day. Don't place your pot in very windy spot, the moss will dry very quickly, especially under full sun.