Oh my gosh, I've actually been there and done exactly that. I'm an upside down backward lefty so I'm always having problems like this. It's so frustrating and it doesn't get better with practice. Sometimes I have a meltdown and just give up for a while until I can face the seam ripping (yes, the seam ripper is my best friend), recutting, resewing, etc.
Thanks so much for making me feel better.