Don't worry -- my grandma joked that there were two sizes of handknit sweaters, too big and too small. My first personal project was a set of Knitty's Cleaves. I used the wrong size yarn, overestimated my width, and didn't check my gauge. Needless too say, it was way too big and looked horrible! That project taught me valuable lessons about gauge swatches, measuring myself carefully, and buying the right yarn. You did great!
Those darn Guage Gods. They're a tricky bunch. I'm still guilty of not perfecting guage or adjusting measurements. That's been the froggy end of many projects. Good for you being able to recover on your first sweater project.