I could have written your post when I was learning the scratch spin! I think, it has been the hardest and most frustrating move I had to learn so far (although learning the camel spin has been a saga, too).
I have been skating for 3 years and after a year I felt like the spin was coming along. When I watched my video, it looked like I was off the spinning axis (my free hip was lifted, so my shoulders were twisting, even though I was spinning fast in the scratch position). This went on for another year.
Now I feel like I have gotten a hang of it, but I can only count on it 70% of the time.
So, hang in there- it is a really difficult skill, even though it is the first one foot spin that is learned. Also, don't give up if you feel like you lose a skill periodically- it comes back. This was another thing I learned the hard way with the scratch spin. Some days it just decides to go, but always returns.
I also learned that if the spin is not working, the more you try it, the more you are cementing the wrong muscle memory. The best thing is to
switch to another skill and come back to the spin. I think my obsessive practicing of the scratch when it was clearly not working, delayed its progress.
Good luck- keep doing it - you will get it, I promise!