OK, first, as far as I know, every state has made it law that the baby has to be 20 pounds AND 12 months. However, the new recommendation (both the AAP and from the safety administration) is that you leave the baby rear-facing until she is too tall (most seats this is when the top of the head is within one inch of the top of the seat) or out-grows the weight limit (most convertible car seats have a limit of 35-40 pounds).
Here's what the AAP says: Overall, children under the age of 2 are 75% less likely to die or experience a serious injury when they ride in a rear-facing car seat...With rear-facing weight limits on convertible car seats up to 35 pounds, most toddlers should be able to stay rear-facing until at least age two. If the toddler is larger, the best option is to keep your little one rear-facing to the limits of the car seat. Rear-facing car seats are outgrown by the weight limit, or when there is less than an inch of shell above baby's head. A toddler's legs hanging over the car seat edge do not play into outgrowing the car seat at all. "
And now most states are looking at changing the laws to 2-years-old. It doesn't matter if her feet touch the seat, my 2.5-year-old is still rear-facing because he's short and only around 26 pounds! His feet touch the seat when he stretches them out, but most the time he just folds them as if he were sitting on the floor! He's perfectly comfortable and doesn't care that his brother faces the other way:)
If you're skeptical watch these couple videos about the safety of turning a 12-month-old forward. They really have found that it's not as safe as staying rear-facing:( In the UK it's law that kids are rear-facing until between 3 & 4! But they have better seats than we do.
This is the true story of a child that was in an accident after being turned around at 12 months (don't worry, I'm not posting a story about a baby dying). http://www.youtube.com/watch?v=Q8gU9zzCGA8
And this is just a general video about car seat safety including crash-test videos I think are worth watching. http://www.youtube.com/watch?v=Y2DVfqFhseo&feature=re...
The odds of severe injury to a forward-facing child 12-23 months old is FIVE TIMES that of a child that is rear-facing. Weight has NOTHING to do with how safe they are, only time develops the spine and muscles enough to make it safe to turn them around - and that is not at 12 months of age.
PLEASE, even if you don't want to follow the newer safety guidelines, at least follow the law and wait another 3 months. But know that if you turn your child around, she is NOT as safe as she could be.