You don't give a temperature or dilution but Kodak recommends 1 to 2 minutes. You may be pulling your prints too soon. Underdevelopment will cause poor contrast and the possibility of uneven development. Print development is carried to completeion. Try developing for 2 minutes.
A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.
Most common cause is under exposure of the film. What do your negatives look like?
I agree, I'd try shooting at a lower ISO before increasing developing time. Blacks in a print depend upon the a negative of sufficient density to expose the paper long enough to get black in the first place. Then the contrast can be tweaked in the printing.
Thanks for all that info. I'm using RC Ilford paper, dev for 1 min so as u suggest I'll try two mins.
And the test print idea. thanks again.
If the source of your problem has been underexposure of the film, I think increasing the exposure at the enlarger will make it worse: you will get very dark prints. If I were you, I would try exposing the paper for a shorter period of time and cook the paper longer in freshly prepared and strong developer.