6 month old obsessed with hands?

This is very normal behavior. How else will she get to know what her hands can do. There is nothing wrong with swaddling your baby, but if you really don't want to, she will definitely learn to fall asleep without it. Babies learn very quickly. Her thumb might even make its way into her mouth and then she'll be able to soothe herself at will. And they stop around 3 yrs. old. My thumb sucker was my best sleeper. I wouldn't worry too much about this if I were you.