I'm so sorry! I feel your pain, as I've done that too, and I've done that with large things like sweaters. Although swatching is important, it's not an exact science. Your tension can change over time, especially over the course of long projects. But you did the right thing to tear it out. In order to finish the project, you would have had to work a lot more, and then fight through a fickle blocking process. And then you'd always look at the project thinking something was wrong with it. This way you save yourself the long-term grief, although you get a lot of grief right now from having to frog. I've gotten to the end of making a sweater, seamed everything up, and realized that I should've just frogged something when I noticed something was rong. Then I end up tearing out the whole sweater.