You should.

A fitting should be about finding a suit that feels comfortable, looks right and gives you confidence. You should be able to explain what you like and don’t like about the fit without feeling pressured into a particular style.

If something feels restrictive, pulls across the bust, sits incorrectly through the waist or doesn’t give you the silhouette you want, say so.
The aim is not simply to make you fit into a suit. The aim is to find or create a suit that works for you.