"Finally, in Oct., 1814, the Massachusetts legislature issued a call to the other New England states for a conference. Representatives were sent by the state legislatures of Connecticut, Massachusetts, and Rhode Island; other delegates from New Hampshire and Vermont were popularly chosen by the Federalists. The meetings were held in secret. George Cabot, the head of the Massachusetts delegation and a moderate Federalist, presided. Other important delegates were Harrison Gray Otis (1765-1848), also a moderate, and Theodore Dwight, who served as secretary of the convention. The moderates prevailed in the convention.
The proposal to secede from the Union was discussed and rejected, the grievances of New England were reviewed, and such matters as the use of the militia were thrashed out."
Found here .
"The meeting opened on December 15, 1814, and was held in secret. Though secession was debated, the action was rejected as premature. The convention did, however, issue a declaration, calling on the federal government to protect New England, and offering several amendments to the Constitution for review by Congress. The final report was issued on January 5, 1815. The amendments were read into the journals of both the U.S. House and the U.S. Senate, but no action was taken..."
Found here
I should also point out that nowhere does anything you posted support you claim that secession was discussed in Washington.