Both of mine stayed in the swaddle til about 7 mos, they loved being swaddled! And I loved it too, it really helped them to sleep. For LO1, we used our own sheets or a light blanket and wrapped him, so it was very adjustable, for LO2 we mostly used the Summer Infant Swaddle Me.
There are some proprietory swaddles which are adjustable - you can leave out one arm, or two, and it changes to basically being a sleeping bag. Have you tried swaddling her so her preferred hand is closer to her face? Some LOs will suck their hand through the fabric. If you leave her hand out completely, she might need a bit of help going to sleep as she's still so little, she may have a tendency to flail her arm about, but perhaps not if she's sucking her hand!