I wouldn't fret so much about never going back to graduate school, especially since you are interested in professional 2-year programs rather than 5+ years PhD programs. If you really want to, you'll find a way back. You have a transition point to try again after your two-year internship is up. Then again, you seem really set on your career goals, so perhaps there is no reason to delay grad school if the job seems so-so.
If I were you I would ask myself these types of questions:
-Do you have ambitions to get into a higher ranked program than the one that accepted you? If so, I'd work and then reapply. You would almost certainly get in to the program that accepted you the first time, and perhaps a few more.
-What about money? Do you feel comfortable with the financial/merit aid package you received from this school? Would it help to earn income first? Do you think your financial aid offers may improve after a few years?
-Will the non-health policy aspect of the internship be a problem, or could you find placements that you think you would enjoy/have some control over?
-Do you expect any major family/lifestyle changes between now and the next time you apply that could make the timing more difficult? (Not that you can always predict these things, nor are they likely to be obstacles.)