Since you don't have a diary, it's going to be almost impossible to tell you why this is happening... Important information is missing! All we know is that you're growing a photoperiod (since you say you've flipped to 12/12) and that you're using FF ... that's it. Please start a diary ... even if you can only reconstruct the last two weeks... then come back and ask your question again (when you finish the last week of whatever diary you can put together, there will be a box where you can ask your question...)
We want to help but we need information!