Economist 2 years out of school in a quantitative role, too late to get into IB?

Hey all,

Timeline: Undergrad (Econ/Math, non-target)->1 year Foreign Master's (Economics, top-tier target in London)->2 years Economist for the Government (not Fed or Treasury)

I realize now after much research that I really want to try my hand at IB, but it seems like I am too far our of school to qualify for an entry level analyst position at a BB and I obviously do not have the relevant experience to pursue an associate role.

After some research it looks as though pursuing a Senior Analyst role at a boutique or going into an MBA program would be my best choices. My work experience includes analysis of infrastructure grant proposals, preparing reports for government executives on the impacts of new technologies, and analysis of regulatory changes; so I am familiar with financial modeling and drafting reports for clients.

Does anyone have advice on what application strategies I could take or what kind of roles would be suitable for someone with my background? I would rather keep the MBA option as a last resort. For what it's worth, I am located in Boston.