Leasha, the trick is to make sure her bottom goes in first, and is on the seam (both with lying and sitting). If you do that you can't go wrong.

When lying it really is a matter of how long she is - she will be fine with legs tucked up, and hanging out a bit is fine too. As with sitting, it looks really uncomfortable as they have their bottom down and legs tucked up, sort of cross-legged, a bit higher than the bottom. But believe me, they are so flexible and used to being in a confined space, so they really love it.

Both my boys were in a ring sling until well after 1yo and always loved it.