"I am the pillow of Michael."
Translation:Eu sunt perna lui Mihai.
It's interesting cause numai and nu mai are a common mistake even native Romanians do.
- numai means only
- nu mai means no longer
So your placement of numai suggests you might have wanted to say nu mai instead. If you indeed wanted to use numai, then we'd place it like: Perna lui Mihai vorbește numai română.