Mine also inflates crooked and off to the side. Looks like it's gonna pop. If I ever need to really use it, I'm going to stand on it and see if I can force it to inflate straight. Regardless, I have a can of fix-a-flat in the car as well, so I have two methods of temporary fixes.
Best place to find a new spare is probably going to be from a wrecked car, ebay, craigslist, etc.