Gerald is correct, re-look at the process and it also might take some experimentation. However I'll add the following thoughts:

They look very flat but there appears to be good shadow detail. With staining developers remember not to judge the contrast by visual inspection only. You really need to print them because depending on how much staining there is, a significant portion of the negative printing density comes from the stain. So stained negatives usually look pretty flat and murky to the eye.

You also might want to consider a neutral or alkaline fixer with low sulfite to maximize stain - although it is still not entirely clear to me whether or not a fully alkaline process makes a difference with all staining developers. Just a thought.