very first I think you should take a very deep look to TI's Kaizen-side and train improvement of your patience with yourself. Get far away from assessing information about your swimming into good or bad or worse. Take them as datas showing you where to work and where to design your own special needed FPs.
Think about Terry (damned I'm missing him), who told about himself, swimming for almost 40 years the wrong way before he started with (never ending) development of TI. And take one
critical part of your stroke and work on that single
FP. Work on this only
and don't think about the infinite parts which are still (or going) banana. And then become familiar with this single FP before you look at the next.
In his 1.0 Effortless Endurance
Terry described it very well how to go step by step. Take that way and let your good coach help you step by step. Success is nearly guaranteed. But have in mind: Succes in FS (even on TI's way) is more a matter of months or years for most of us.
And once more Terry: Most things we have to do in FS is against our instincts or reflexes. This makes it so difficult and so interesting.
At least a partial response to your main question. The receptors for proprioception are intrinsic and are directed for our mostly upward standing/moving in air and on ground. They simply don't work so well when horizontal and in water as environment. Even people who where born without receptors for proprioception or lost their function by illness can learn to walk and move. Eyes are extremely important for this learning, in darkness they'll break down at once. In water we can learn another way of proprioception with FP-work, awareness to our skin and body to different tiniest perceptions. Someone are able to feel it at once, others do need a fairly long time (long mostly perceived by the swimmer himself...).
Cathy, find back to enjoy your improvement-process. Play around and be glad you found something, you're not able to adapt at once and real work and (emotional) effort is necessary to learn. Believe your coach in your (only for you!) small steps forward and enjoy them. I'm sure if you'd ask Shinji, he knows many more points in swimming he'd like to improve than he could say he mastered.
So enjoy your way and let us participate in your improvements and your problems... perhaps one for one post :-)
PS: Could swim BS from childhood, started FS around 60+ and some months later with TI, became a TI-Coach with 65... Worked nearly a year on a known fault, worked on the symptoms and lost (unconscious) some foundations of TI, was shocked from a video which showed me swimming a beginner's stroke... Took some time, work and help from others to find my foundations again... Kaizen-steps never end... And you're not alone, Cathy...