Looking at the scans I assume that is? Which have been auto corrected by the lab no doubt. How do the actual negatives look? Nice and contrasty with strong blacks? flimsy and grey, feint? Are there edge markings?
You need to narrow down a lot of variables: User error, camera error, film problem, development problem, scanning problem.
So I'll ask again, can you be 100% sure that the camera's exposure is correct? Can you compare it to a separate meter/digital camera?