I can relate to this thread... I got my first tablet almost 3 months ago, and I'm still not used to drawing on it It just doesn't feel right. But it's kind of opposite to OP's problem; I actually can make doodles with it, though it doesn't feel as natural as it does on paper, and turning them into something more finished is extremely hard.
Keeping track of proportions, making fluid lines, adding details, etc. - all that is so much more difficult for me digitally, even though it is already plenty hard on paper... I go through multiple layers of rough sketching and it still doesn't look even half as good as it would on paper. Does anyone else have this problem? Like, not with doodling, but with doing "finished" digital works?
I spend many years wishing I had a tablet, and now I'm just frustrated with how the transition to digital art actually made my poor skills even worse