I'll give 1:30 a try next time.
I'd suggest a range of possible factors.
Pulling the print early is always a sign of a problem - give 90 seconds and adjust exposure and contrast, not the time in the developer.
The developer should not be colder than 20C as this will have pretty much the same effect as pulling the print out early. A couple of degrees over is not a problem.
Check your safelight and any other lights in the darkroom (light leaks round doors, red lamps on extension cables etc.) as any fogging exposure can interfere with the light you are choosing to squirt on to the paper. Even if the fogging exposure isn't enough to make a tone on it's own it will affect highlights especially.
How are you filtering? With a colour-head or filters? Confirm the values with the instruction leaflet in the pack of paper.
Use stop bath (as recommended by Ilford). Paper carries over far more developer than film and remember that water-bath development (google it) was once a way of reducing contrast. Developer carryover will also quickly kill your fixer.
Thirty seconds in the fixer is the minimum time at a minimum temperature of 20C. Where you are using easy-to-wash RC paper you can safely allow a little more time and give constant agitation. Be very certain that you are using a 'rapid' fixer at film-strength (1:4 for Ilford Rapid) and not the older hypo-fixer (in either case you would need a much longer fixing time). Under fixing isn't going to help the print in a few years time . . .
Read Bob Carnies enlarging thread, here.
For this particular neg, there is tone even in the jumper so you should be able to get that barely visible in the print too. Start with Grade-3, take a stop and a half off the exposure you previously used (remembering to also allow for the speed-change across grades, if you are using filters), to see what you can do with the subjects face, it is where everyone looks in any portrait, adjusting time until the face looks ok. Only then adjust the contrast, if necessary, to change the darker tones towards where you want them - additionally the dark jumper and jacket could be burnt in with grade-5 a little, in order to make the darkest parts go just to black for example. The plain background might also want slight darkening in the corners, for example. Remember that you can add tone and black by burning in, with appropriate filtration, so the basic exposure is the one that just gets you the starting point of (for example) the face - of course, sometimes it is more practical to dodge a small area than to burn-in, it depends on the scene.
Make notes of everything which you are doing. You can usefully make a short series of prints of the figure, with half a sheet of paper centrally, at grades 1 to 5 while adjusting the time to keep the face about the same tone. It will help you as a comparison for your next test-print to suggest the direction for you to adjust in.
I have no clue what I'm doing, so read what everyone has said. ;)
+1 to what Martin says above.
I'll add that you should make a test strip to determine print exposure and that you should use the print highlights as your benchmark. In other words, find the enlarging time that gives you the highlight values you want. Adjust contrast to get the blacks you want.
If your enlarging times are too short (and a thin neg may be the culprit here, especially if you need a rather high contrast grade), then stop down or use neutral-density filters to get a more manageable time.
If you have a color head, you can dial in neutral density by using equal amounts of yellow and magenta (cyan isn't needed for black-and-white printing). This will give you longer times.
Even if your negative has shadow detail, it may be "thin." This could be due to underdevelopment or a low-contrast subject. In either case you would need a higher contrast grade than normal for the print. If this is consistently your problem, then increase your film development times.
Underexposure will also result in a thin neg, but the shadow values are not recorded. This results in less overall contrast and prints with gray shadows (not black) when printed at normal contrast and inky black shadows and heightened contrast for the mids and highs when printed at a contrast grade that gives a full range of white to black.
Hope this helps,
If your negative is too thin, then you have to figure out whether your exposure or development went wrong. There is a multitude of reasons why this could be the case, and merely following prescriptions is not always a guarantee that you will get a good negative. It is easier to determine the cause if there is a constant bias somewhere. Sporadic inconsistency is much harder to deal with. Getting the negative right is where I would start if I were you, but of course that won't rescue this particular image.
My exposure times from 120 for similar paper etc are around 16 to 32 secs at f16, using Ilford MG filters. I almost never have to go to grade 4 or above, and for the most part I am around grade 2 or 2.5 for the base exposure. I sometimes use the extreme grades for additional burning in, but I am not very good at it yet. So in short, I don't think you can blame the enlarger. It seems the negative is the problem, if other possibilities such as fogging can be eliminated. For the sake of comparison, what are your exposure times normally? (For the same negative size and degree of enlargement, of course). Under- or over-development or exposure can have a marked impact on print exposure time, more so than you would guess with the naked eye, and more the higher the contrast you print at. I once had TMax 400 completely over-developed in caffenol, and ended up with negatives that needed 2 minutes exposure or more, at grade 1 or thereabouts. The amazing thing is that one can get a print from a way too dense or thin negative if you know how to work with it. Still, life is easier if you get good and consistent density in your negatives.
You could also dial in equal amounts of CMY filtration on your color head to get a longer workable exposure without changing other aspects of your setup.
Why not just run some more test strips? How bout f16 and 4, 6, and 8 seconds? That print looks typical of a one of my first efforts with a new negative. A good place to start.