Am I wrong in that interpretation?
"Arkansas, Texas, Louisiana, (except the Parishes of St. Bernard, Plaquemines, Jefferson, St. John, St. Charles, St. James Ascension, Assumption, Terrebonne, Lafourche, St. Mary, St. Martin, and Orleans, including the City of New Orleans) Mississippi, Alabama, Florida, Georgia, South Carolina, North Carolina, and Virginia, (except the forty-eight counties designated as West Virginia, and also the counties of Berkley, Accomac, Northampton, Elizabeth City, York, Princess Ann, and Norfolk, including the cities of Norfolk and Portsmouth[)], and which excepted parts, are for the present, left precisely as if this proclamation were not issued.
And by virtue of the power, and for the purpose aforesaid, I do order and declare that all persons held as slaves within said designated States, and parts of States, are, and henceforward shall be free; and that the Executive government of the United States, including the military and naval authorities thereof, will recognize and maintain the freedom of said persons.
You are quite correct. The theory behind the Emancipation Proclamation was that it was a war measure. In essence it confiscated the property of rebels. It expanded on previous Confiscation Acts that put somewhat less extensive abolition measure into effect.
Lincoln made no attempt, in this proclamation, to free slaves in areas not presently in rebellion, on theory that he had no power under the Constitution to do so.
It should be noted, however, that Lincoln repeatedly encouraged and supported abolition efforts in Union slave states, including offers to provide federal funds for compensation of slaveowners.
This resulted in emancipation in all but two Union, and several occupied, states before the end of the war. So that 13A freed only about 50,000 slaves in KY and DE. 98.75% of all slaves were freed before the war ended.