Have you done more than just cast on? The cast on row isn’t as large as the finished project, so maybe you need to work a few inches and then measure it. And even if you’re using larger needles, if the yarn is thin it may not come out as large.
Well, I am not expert but I don’t think casting on 64 stitches will go very wide no matter how big the needles or the yarn. That is just my thought. Maybe it could be a table scarf?
Is it possible it’s knit in strips that you later sew or crochet together? Sewing is a pain, but strips are easier to knit in the long run because they aren’t so heavy in your lap.
Are you sure you’re using the right yarn and needle size? 64 stitches with worsted weight on a size 10 needle will be approx 20 inches long or so. But if you were to use several strands of a bulky on size 17 or 19 needles, you’d be approaching a lap sized afghan size.
Is the pattern online somewhere where we can have a look at it?