I just have to +1 pretty much what everyone has said. You really didn't mess up. You may not have followed the process exactly, but who cares, it's home brew. You do it for fun and because you can. Experimentation, either intended or not, is a big part of it. The only way to really screw up is by improper sanitation, and even then, I know a few people who are a little lax when it comes to that part too. I personally don't take gravity readings. I also wouldn't pitch more yeast. Just let it do what it's going to do. Patience is the key. If you're very concerned, let it sit in the carboy a little longer than planned. Time is your friend with the homebrew.