butterfly kick

hello I have been swimming fly for 5 years, but just a week ago somebody told that my stroke is wrong. When I first learned butterfly I used to focus a lot on my kick, so my stroke was very slow. Then my coach told me to focus on my arms, get them fast and my kick would eventually catch up with the speed. Then I kept on doing fly but wihout a coach, I eventually got faster, but here is why my stroke is wrong: I don't kick two times every stroke, I only do it once, and anybody ever told me! So, my time for a 50 fly SCM is 32" high, and for 100 SCM is 1' 13" I started to do 2 kicks every stroke, but my times are x10 slower, like 40" for a 50 SCM fly :cane:(the only positive thing is that I get a lot less tired than with the other stroke) Here is a video of me from 6 months ago: ‪50 fly SCM‬‏ - YouTube There you can clearly see that I only kick once every stroke. So, my question is, how do I correct my stroke without losing too much speed in the process? Because with the current speed of my arms, there is no way to kick two times, so I have to slow down and let them still infront of me for a moment so I kick a second time. Thanks