ترجمة - إيطاليّ -انجليزي - Mi sento che mi manca qualcosa... forse sei tu!...

"so solo che non so!" lo avrei tradotto con "I just don't know!"

mi sono innamorato di te: I fell in love with you.
Regading the last sentence, Lilian's version emphasizes what he knows and what he doesn't know, the same as the original, but I think that Alessandra's version is not a bad idea either.

... Maybe I fell in love with you. I only know that I don't know!