If it's really what you want to do, then go for it. I have no idea what the demand is like in the northeast, but here in the midwest there is a real need for people who are willing to work with children and adolescents. The only advanced practice nurses I know who are having difficulty finding jobs/partnerships are those who are in women's health because so many ob-gyns are dropping obstetrics.
The subspecialties of psych APRNs are family psych/mental health NP or adult psych/mental health NP and child and adolescent P/MH CNS or adult P/MH CNS. In some states, CNSs do not have prescriptive authority while in other states they do. I'm in a program where there is no difference between the education for CNSs or NPs in psych. I started out planning to take the exam for child and adolescent CNS, but have decided to do family psych NP instead because 1) some states do not allow CNSs to have prescriptive authority and we may move to one of those states, and 2) I like the more holistic option of being able to treat the whole family.
If you are an NP, you may be able to do quite well by simply doing medication management for non-prescribing therapists while you build a private practice. You could join a pediatric or family practice or join a practice with a psychiatrist. Community mental health is another option. There's also a trend for NP only practices. I don't agree at all that an advance practice degree will only suit you for administration or that it is narrow in scope. I think that having one person who can manage meds and provide therapy is a great advantage (assuming you're not in a program that doesn't teach NPs as much about therapy as it does CNSs). I can never keep it straight who will reimburse whom for what and it is different in different places, so that is one consideration.
good luck with whatever you decide