How do you like the fabric on that size needle, is it stiff or flexible? How many sts per inch? And how long is it? Just an inch or so of knitting can measure wider than it will be when it's all knit up, so you need more length to get a better idea of the width. If the fabric is really stiff, you really need to use a larger needle, though that means adjusting the number of stitches.
Did you see the gauges that are needed? CO about 30 sts and knit them in the patterns given - both the shadow rib and the banjo cable. That will give you the sts per inch you're getting then multiply that times the size you need, 44" and that will be the number of stitches you need to CO.
sue- knitting heretic