switch to 12-12 NOW!! she's already in flower. flowering now will mean a little less in the end but will be just as potent if you take care of it.

you can't change the light cycles like that though. as stated before, it stresses the plant. put her on 12-12 as soon as you read this post. don't think, just do, then read the article "pre-flowering and flowering" in the college link in my sig.

hope you're not too late,
kp