You might want to just rip out the back and redo it. We needleworkers rip out things much more than anyone would guess. And beginners resist ripping out at all costs. But unless you do not mind how your finished project will look, and unless its unevenness will never nag you, rip it out.

Xcalibur, I'm guessing from the name of your pattern that you start at the bottom edge of the back and keep going till you get to the lower front edge, so that you have one long piece that is folded in half at the shoulders? In that case, ripping out would mean undoing at least half the sweater.

You may be able to ease in the extra front length when you sew the side seams. It will depend on how firm the knit is. If it's soft & stretchy yarn, it will probably work.

That's pretty normal for a beginner's tension to loosen up. I think we all pull the stitches too tight at first!

Thanks to both of you. I decided that it wouldn't be too much extra trouble to sew the seam (I've already knit one of the sleeves) and then rip that out too if need be. Well, I've sewn it, and it looks good enough to satisfy me.
Thanks.

Glad to hear it! The next one will be better, and the next one after that better still. Keep on knitting! :D

Many of us find that our gauge changes once we get up to speed. If this is the case with you, I suggest you have a "practice" piece that you knit away on until you get limbered up each time. Also make sure you're sitting in the same position and that you're not upset when you're knitting, because that will throw off your gauge quicker than anything. Every bit of tension we feel - physical or emotional - flows right out of our fingers and into the knitting.

Congratulations on finishing your first sweater! This is a very big deal, and welcome to the world of knitting!

It is true that your gauge changes as you increase speed, and this will continue to be true - every time you try a new patter or technique your sizing will be a little off.

Don't forget that you can (should!) smooth out many of these variations when you block. And you should block everything, even synthetics. The fluff weaves together a little and locks in the stitches for longevity. So when the material is damp, push and pull the length and width to get the sizing you need. Always block with a measuring tape, not just your eyes.

Good luck!