Sorry if you are struggling with the kick. I don't include too much of it because triathletes hate it generally, but I also know that the fastest triathlete swimmers are great at kick. So it's good to practice it :-)
I have a few points that might help.
1. You might be bending your knees too much, which can create drag, make you sink and slow you down. Remember that the kicking motion comes from the hips, not the knees. Just keep your knees soft and supple, not bent or locked straight.
2. Keep your toes pointing to the wall behind you, to aid streamlining. Whereas if your toes are pointing to the tiles on the bottom of the pool, your feet will act like water brakes.
3. If you get desperate, try kicking with some medium length fins as an aid. While still practicing the above two points.
In addition, it's always a great idea to get video swim analysis if you can find it anywhere. There may be other elements of your stroke or body position that are effecting your kick. Swimming is a learning journey that never ends.