This last post is very helpful on several different levels.

a) First: I get that you don't believe you are an "Arnie." However, when I read the description and watched the videos, an "arnie" or maybe "overglider" is what I would have guessed your style is. To my eyes, the primary characteristic of these styles is the lack of body balance in the water: feet are low, hips are too high, pull is with a straight arm or severely bent elbow, kick is from the knee. These styles suggest a swimmer trying to swim on top of the water instead of through it.

b) Second: Using a 6 beat kick does not mean you have to go fast. A 6 beat kick simply means the number of kicks per 2 arm pulls. If your legs are getting that tired from 6 beat kicking, you need to change your technique.

In a post in January 2018 (Face Down Floating), I showed one way to get comfortable with body balance. I suggest you find that post and see if you can float like the video. I also call it "streamline floating." If you find this hard to do, I encourage you to spend the time to figure it out - even at the expense of less laps. A favorite saying of mine is "You cannot train enough to overcome inefficient technique."

Good Luck