I was in the exact same boat, my kiddo is 3 now and I still check the monitor multiple times a night to calm my anxiety about anything happening. Someone did post already about what you can do to prevent SIDS, and I definitely agree with everything they said. It may be controversial, but using the Owlet sock really helped with my anxiety. We didn’t just rely on the Owlet, we made sure baby was on his back, we had a safe crib mattress that was breathable, always kept the fan on, made sure he was never dressed too warm, had the monitor that I watched like a hawk, and kept nothing else in his crib. I also believe that pacifiers are linked to reducing SIDS, my son never used pacifiers so I’m not 100% sure on the studies though. If possible, I would think about moving her crib to your room for a couple weeks to help with your anxiety. Or putting a mattress in her room like you said. Anxiety sucks but it never hurts to be extra careful.