Startle Reflex

My 11 week old baby still has a really strong startle reflex. Trouble is, she has refused to be swaddled since she was 2 or 3 weeks old. She prefers to sleep with her arms above her head. It doesn't seem to bother her for the first half of the night but after her 3am feeding she spends the rest of the night fussing and slapping herself in the face. It would be funny if I weren't standing next to her crib rubbing her chest and holding her pacifier in to help her settle from 4am-6am. We bought a Nested Bean Zen Sack and this is our first night trying it. Fingers crossed it helps. Does anyone have any tips on what's worked for them?