Hi, I don't have the book, so I don't have the whole pattern. That would be very helpful. I did go to Ravelry and look at a picture of the sweater. (I only looked at one picture, the one on the pattern page that comes up.) According to this picture all the colored stripes are the same width, the information there says it is made of 8 colors. At a gauge of 28 rows make 4 inches, a stripe of each color in the back would take 112 rows and end up 16 inches long.
I have worked the striped sequence 14 rows each in each color.
All 8 colors or only how many have you actually knit on the back? If you did all eight you would already be to 16 inches long and 41 more rows would take you to about 22 inches and then another 23 rows would be about another 3 inches. We're getting pretty long here, up to 25 inches long now.
But you say, after the whole works that it says,
At this point, they tell me that it should measure approximately 10 1/4 in in length.
You said yours is turning out quite a bit longer. How is your row gauge? Are you getting 28 rows= 4inches or very close to that? It sounds like things are not adding up.
I suspect that you have not really done stripes (or shouldn't have, if you did) of all eight colors before the shaping they give starts. Have they given the directions strictly going by the number of rows instead of inches? I would think they might on a pattern like this.
It seems like it may have told you to do so many stripes of 14 rows each in a given sequence and then starting here to work 6 rows in whatever color should be next in the sequence and then over the next 41 rows you are going to be adding the increases on the 1st of the 41 rows and then on the following 11th, 21st, 31st, and 41rows, all the while keeping to the sequence given and making sure you have 14 rows of each color. After you have all that done you continue evenly, changing colors every 14 rows to what ever color is next in the sequence, for 23 more rows. And your total length should be near 10 1/4 inches. (Somewhere there in the pattern it should give the sequence of colors.)
If your row gauge is way off the length will be quite different than intended. What I suggest is that you go back and read the pattern again from the beginning and be very careful that you have done exactly what it says, and didn't get off track somewhere, and that you make sure your row gauge is very close to what is given.
I have a general question about the pattern. Is it done in several pieces----a back, 2 fronts and the sleeves all separate? Or how? Are you working top down or bottom up? It seems like usually if you were working a separate back piece, from the bottom up that you would expect the shaping at the armholes to be decreases not increases. So I thought maybe you were working the front and back at the same time and the increases are the shaping seen in the front. In which case the shaping should start pretty soon into the piece. The numbers would seem to add up better that way I think.