Can anyone give me advice on how to gain back trust in EU authorities.

You don’t. Stay critical. Sometimes they get stuff right, often they don’t. There’s nothing to do about that than to demand consequences and independent control instances. Vote for parties who want that too or get political yourself by joining a party and talking to people about your ideas. That’s how democracy works. It’s slow and most of the time it sucks. But it’s the best we currently have. Let’s hope it gets optimized.