Gray Maine Coon mix with orange collar

I lost my gray Maine Coon mix cat yesterday around 3pm. She's a medium-large longhair with a white chest and a tiny white heart-shaped patch on her belly, and she wears an orange collar with a small silver bell. I last saw her outside a cafe on Exchange Street in Portland's Old Port, and she bolted when I was juggling bags. She's been with me for about 4 years and has sentimental value, and I'm really worried; if you spot her, drop me a message on the app so we can coordinate.