For printing I have found the paper with the most contrast is Ilford MGIV. You may try a 47b filter with the paper you are already using which, depending on the paper, could give you just a little more ooomph. You could also try to find some old graded paper. Agfa made papers up to grade 6, but they probably will have lost some contrast by now. You don't say what paper you are using, but Kentmere for example will never reach grade 5 which could be your problem.
Overall the best thing to do I think is to overprint it a little and gently bleach back the highlights. This will more closely resemble a normal print than using a high contrast or lith developer since the bleach won't affect the shadows much. A high contrast developer will tend to completely dump the shadows. Bleaching may shift the tones a little toward the warm side in the highlights.
If this doesn't work for you, you may try intensifying the neg (even though you state you don't want to). There are many methods for this but the easiest ones are Selenium toning, Sepia toning, or bleaching and redeveloping in a staining developer like PMK or Pyrocat. If you are almost there with a straight print this could put you over the top. I have saved more than a few images doing this.
Hope that helps.