That is one of the problems in flowering with CFLs...the light is only effective within about 6 inches from plant, max. Lower/interior branches will never get enough light to develop anything tight or worthwile.
As soon as you see the pistols (long white hairs) it's officially in flower. As soon as you see the trichomes starting to cover the leaves, and start turning milky-colored, it's almost ready for harvest.
Yield: don't know. With an HPS light in the flower room, I'd say you have a chance that the bud will firm-up, but with CFLs the plant will have less energy available for it to produce, so yield will suffer. (like asking a professional weightlifter to live on one twinkie a day, for 3 straight months before the main event.
My guess...1/2 to 3/4 oz max.

How many weeks of veg? May have started flowering too soon, which can stunt its growth and development. (is always trying to catch-up) My guess is she has at least a few weeks to go.
Keep feeding her, and do you have a fan? This helps the stem strengthen up, and fresh air is always a plus.