Hi, glad to have you join us.
I think your needle might be a little too long for the stitches you have at the moment. You can look on the Advanced Techniques page for the Magic Loop technique, though you might only need to use the single loop version for a few rounds, then your stitches should fit a little better. Basically, pull out the cord between 2 sts about 2/3 of the way around, making a loop in it. That 'shortens' the cord so the stitches won't be stretched out. Then knit to the loop and do it again. After you have 4 or 5 rounds, you might not need to make the loop. Here's a video to help you out - http://www.youtube.com/watch?v=qyd0BkKC8tU