Yeah I came to the same conclusion. Sorry if this is repeating what @VILLAMARV has just said, but I spent a few minutes working this out, and I’m tired and hungover and I can’t let it all be for nought.
Let’s say the two teams not winning are Bristol City and Derby. We win, we’re on 75. They both draw and Boro win, Boro are on 70, Bristol 67 and Derby 65. With two games left, Boro could overtake us by one point as could Bristol City if they win all their remaining games.
So in that instance, no we wouldn’t have sealed it. If Boro draw, they can only reach 74 points. I think it can be sealed tomorrow (discounting goal difference), but we have to win, Boro have to drop points and one of Derby or Bristol City do too.