Indeed, there are no real blacks in your print. What grade did you print this at? If you can go higher, it's worth a shot.
Btw, it's debatable how deep the blacks need to be in a print, especially a portrait. To a large extent, the eye adjusts to the density range it's presented with and accepts it as normal.
I mostly see severe newton rings in your print. Are you using a negative carrier with glass, and have non-AN glass installed? Is this what you may be mistaken for 'water marks'?
Always develop paper to completion! Depending on the paper and developer used, this is between 1 and 4 minutes, most of the time. Very concentrated developer on RC paper will develop to completion in a minute, with FB paper and concentrated developer usually 1m30 or 2m00 is allowed, and anything upwards depending on developer activity.
Never pull a print from the developer 'because it looks good right now', unless you're lith printing (and you're not) or you have a very specific purpose in mind (not applicable here, it seems). If your print comes out too dark when you develop to completion, give less exposure. If that makes the contrast too low, increase contrast grade. If you print at grade 5, develop your paper to completion and your prints are still flat, you're SOL and need to work on making better negatives