I'm left handed and I never really learned a good grip I could write with. So I've always struggled with handwriting. I also have an essential tremor in my left hand. As I have aged, the tremor has gotten worse. So now, I have to grip tight to minimize the tremor.
I've pretty much given up on handwriting, it's embarrassing to either try to write, or have someone else write stuff for me. I ask my wife to fill stuff out for me all the time, but people probably think that's weird when they see it.
That sucks, sorry to hear it. Have you tried seeing if a tablet handwriting recognizer can be trained on your writing?