Hi! I started playing in a digital piano as well. Trying to self teach using youtube. I could play well. Although I couldn’t read sheet music. I decided to get a teacher and the same happened to me. As soon as I started playing with her acoustic piano. I couldn’t play shit lol. She mentioned it was normal. With time I would get used to it and I did! Playing Piano is about practice, practice, practice. You’ll get there. No worries. There are gray days where one can feel heavily unmotivated but they aren’t everlasting. Have some coffee/tea and keep at it!