Can't see the wood for the trees
Meaning: If you can't see the wood for the trees, you can't see the whole situation clearly because you're looking too closely at small details, or because you're too closely involved.
For example: I don't think we can see the wood for the trees at this stage, so let's get an outsider to take a look at the project and give us a progress report.
In Portuguese: Não conseguir separar joio do trigo.
Note: The U.S. equivalent is "can't see the forest for the trees".