If you're worried about her safety (e.g. suffocating in the tangled blanket) then I understand your decision to quit swaddling. However, there really is no reason to be concerned if the blanket you're using is lightweight. Wrap it around your own face a couple of times to be sure that breathing is still easy. At six months old, your daughter should be able to move things away from her face anyway.
If you're still concerned, you might consider buying one of these: http://www.miracleblanket.com/
or these: http://www.thewoombie.com/
Truthfully, if you're using the proper blanket, there's no REAL reason (health or developmental) to quit swaddling until it's no longer an effective way of putting your child to sleep. As a mother of two, I can tell you that ANYTHING that helps your baby sleep is a blessing that should be cherished and exalted on high for as long as possible.
There will be many "stages" that you'll have to go through as a parent and many night-time struggles that will result. So my advice is to choose your battles wisely. Honestly, swaddling is harmless. And if it bothers you that people might think she's too old, then don't tell them. Problem solved!
Best of luck to you, E.. :-)