Hey, KW --
Let me log in on the side of your professor, but for some other reasons:
*Education should OPEN doors for you, not close them. An MSN (with or without the NP) will do that, I assure you.
*Options Increase with an MSN -- at 27 it may not matter, but at 47 you may want to teach (MSN required)or consult (MSN prerequisite) or get a PhD (or DNSc, or JD, or something) and your MSN can launch that, another BS won't.
*Independence and Autonomy are probably things you are seeking in nursing, while they are not always easy to achieve, the PA is NOT (under current medical statute) much of a route to such pursuits.
*Personal Growth -- education is good in an of itself, whether it gets you to a specific credential, a goal, a job, or just increases your self-awareness, independence, breadth of thought and network of other thoughtful people.
Have a great life and practice, and let us know what you decide to do.
From an MSN, and PhD who's been there.