Hi Lowena, the standard way to adjust tension in knitting is to use larger or smaller needles, but I'm sure you know that and in your case it won't help as you are wrapping the yarn so tightly around the needle it is in effect strangled and the stitches won't budge never mind have room to get the other needle in.
Are you tense yourself? When you concentrate on something do your shoulders get tight?
There are lots of different ways to knit so perhaps try another method and learn it like a new craft rather than try and unlearn what you currently know. There are lots of YouTube videos on knitting methods. Maybe have a go at a couple and see if it helps.
Most of us learn knitting as children when our hands are small and our patience limited so keeping stitches on the needles was achieved by pulling. I can still remember struggling with horrid bendy plastic kids needles and my hands were clammy and nothing went smoothly and then suddenly all the stitches fell off.
Recently I have been using interchangeables and a cord and apart from their portability I find it helps that the weight of the knitting is taken by my lap and I do not have to balance and manoeuvre long needles.
I'm having my kitchen gutted next week so how about me coming down and helping you rather than standing around in half a building site making endless cups of tea.
Don't give up