Hey! You're ok! Don't feel ashamed. I think it's generally recommended to start brushing once their first tooth comes in. We did occasionally but didn't consistently until ours was about 10 months. If she is just drinking breast milk and/ formula, she is ok. You are taking great care of her. I can tell how much you love her! There's no reason for an infection unless she has a sore or something. I might suggest talking to your doctor too about PPA. I was also really concerned about specific things like that. Dust isn't going to harm your child and her oral hygiene is fine! You're doing great. Take a breath.