Kathleen Power square in north american afghan 2

chart b row 1 69 stitches (RS) SL l, ssk, k2, pd, [K1,p7 6 times, p3, k4. my understanding of ssk is slip 2 and knit 2 together. following this thinking i am short stitches at the end of row.

It sounds like you may be decreasing too many stitches… To SSK you slip one as if to knit, slip one as if to knit (or purl), then slip the left needle into the front loops and knit those two together through the back loops.
View the video for SSK here to make sure you’re doing it correctly.