How To Improve My Input On The Ui In Work?

For context:

This piece of work has poorly defined requirements so the devs have a lot of input on how something should look.

We have no ui team, only a contracted team who ran out of time and gave mockups that we need to chop up to make right.

My issue is that whenever I get an idea of how I would like the ui, it’s almost always shut down as a bad idea. Which is fair enough, I’m openly a purely functional guy when it comes to UI. But my question is how can I improve this skill?

My current ideas only come from sites I use and like, so i think either my taste in ui is actually bad, or just doesn’t align with what my business expects.

How would you navigate out this rut if you were in it?