That yellow light is perfect for flower u could use just that if you had to you could also add one or the 6500ks with it so basically take the yellow.one 2700k and a 6500k one and put you plant on the 12 12 cycle with a timer with those two lights it will work
You should get a timer and have the plant yojr flowering in a separate area by itself also your not supposed to use 6500k for flowering you can mix between the two spectrums of 2700k and 6500k but you need more 2700 k (red) during flowering I'm gonna look up on that light you have that is yellow...
Cfls sometimes take longer to grow what cfls are u using when I grew in the past I used two 27 watt 2700k LEDs and 1 3000k 13watt cfl to flower and had great results and vegged with 2 23watt 6500k cfls and 2 13 watt 6500k cfls don't listen to what most.people on here are gonna say about.lights...