Letting Go Means Taking My Feet Off the Bottom

I want to learn to swim, at the moment I have to build up to getting into the pool and wade about a bit before pushing off in the water with my bottom down and feet only inches from the floor. However that in itself is a big move as a few years ago I couldn't take my feet off the bottom at all. Now at pushing 70 I am still struggling with the urge to learn how to swim correctly. Last week I had a couple of lessons one to one. First lesson went reasonably well and I managed after a couple of years out the pool to lift off and swim a very short length. Next one not so good, she wanted to see me float star like, face down in the water. Logic tells me that I should be able to do this and once mastered swimming with my bottom high up to the surface would be a doddle, but the fear and panic is so great I just cannot master it. I knew, that she knew, this process might take more than the odd lesson she was envisaging for this old woman.
In my paranoia I believed she was now seeing me as a hopeless case,  that I was so stuck in my ways of doing this half hearted splashing about, I couldn't grasp the floating bit.
I have been trying to work out what I am afraid of, apart from drowning of course. Logic tells me that isn't going to happen. With either a swimming instructor  there or hubby, who has assured me of his support,  but sadly, and ashamed as I am to admit it, I do not trust them. Deep inside I don't think I trust anyone and the only way I can stay above the surface is to stay above.
There are those who tell me to use the buoyance aids available, but I don't trust that either. I know what your thinking that I am a hopeless case and of course that is a projection too. I have seen that there is a session at the local swimming pool for 'nervous adults' and wonder if I should give that a try? Lessons start next week for adults so that is another option.

I think that all of this is a metaphor for the way I live my life, and recently have come to realise that as I age the more independence I strive to be. If I am ill it is very hard for me to ask for help and if I don't then those around me see me as not needing anything.
As a child I made a decision that the adults in my life, my family, were not OK and could not be trusted to look after me. There was always turmoil in the household and I felt a permanent sense of anxiety. In retrospect it felt like stage fright on a constant level. Whenever something new had to be faced I would tell my mum that I felt sick, mainly because I didn't know how to describe it. That nausea was a physical manifestation of my deep rooted fear. There were so many things went on as a child that were frightening I learned to stand it and tell no one. Violence at home, bullying in school and an inner isolation which manifested as standoffishness.
Knowing all of this does not help me swim or let go in the water and I wonder if after years as a therapist, and all the personal therapy I underwent, will I ever even trust myself to let go, giving up what I perceive to be complete control. I suspect that if and when I do, then swimming will be easy peasy lemon squeezy.