There are very few patterns that truly unique - and lots of people may have come up with a similiar idea. If it truly is your pattern, I would contact the sites - they seem to be forum/ sharing kinds of sites.
Tell them you are concerned that a,b,c patterns (don't make them look, include links to the patterns) were written by you and you sell (again give the links to patterns you say have been stolen. None of these are individual sites, any one of their members could have uploaded it. Be polite, be precise in what you want done - take down the patterns (honestly they can't do much more)

Even if you didn't design the characters, you can still design patterns to make them. The problem would be if you sold the characters made from the patterns (that's where the copyrights come into play)

Most reliable sites will remove the pattern. Ravelry is a good example of large site that does the same. Even there though you can see a pattern that is for pay (either by download or link to another site) that is the same as freebie. There are very few unique patterns for knitting and crocheting out - new fashions, new ways to embellish (ie make characters) but very few things that are truly "new"