Hungry baby formula is intended to fill your baby up more, so that they will need less to feel full. It contains the same nutrients per ouce as non-hungry formula. If your baby wants/needs more ounces of 'standard' formula per day than is recommended for their age/size, that's when you should use it.
At 11 weeks my HV told me she would expect roughly the equivalent of 5-6oz, 5 times a day. So, I would've thought your LO might be a candidate for it - but it's a good idea to talk to your HV first.
Because it fills them up more, your LO will either take less at the same intervals, or have the same amount at longer intervals, but still be satisfied. Over time and with growth spurts their demands will change and increase anyway. You might find that their weight gain drops a little in the short term as you are cutting the amount of nutrients they are getting - but that isn't necessarily a bad thing if they are still gaining well. Again, talk to HV or you'll get questions at her next weigh-in!