creating bad habits?

My 3 month old will typically only nurse to sleep and she'll only take naps on me. She used to nap in her swing for 3 hours and I would just put her in there, give her a pacifier, and she'd go to sleep within 10 minutes. Suddenly she just stopped taking a pacifier and won't nap in her swing. She'll only nap in my arms. I don't know what to do! I want to start putting her down for naps in her crib, but as soon as I put her down if she's asleep she wakes up and is looking around and then eventually starts fussing. Does anyone have any advice?! I feel like I've created bad habits with her!