Really need advice about my daughters self image issues

She is a month shy of turning 5 and the past couple months she's been getting so hard on herself. She's constantly worried that people are going to think she's weird, she's afraid certain clothing makes her weird, thinks her arms are too long, calls herself stupid and when she gets mad she will pull her hair or squeeze/pinch herself. Whenever we go to a public play place or something if a kid looks at her too long or says something casual she will sometimes be really mean thinking they are out to get her. I don't know if this is kind of a common phase or not but it is absolutely breaking my heart. Every time I think of it I start tearing up or full out start crying. (I'm also 3 weeks post partum so extra emotional) she's starting school next week and I'm soo excited for her but also feeling very worried. She's a beautiful, sweet and goofy girl and I want her to feel good about herself and not worry about what people think of her. It feels worse because Ive known that feeling my whole life. Being made fun of and worrying about what people think and assuming everyone is out to get me all through childhood and still to this day. Im heartbroken that this is happening to her. I'm starting to beat myself up wondering if I have caused this by complaining about my body/clothing sometimes. Need help and advice please of other people's experiences and maybe some activities we can do together to help boost her self image/self esteem. Is this normal for her age? I've always taught her about her feelings and we talk about things alot but I'm also not perfect. The past 10 months of going through pregnancy was really rough and I wasn't myself, always angry and irritable and I worry that I caused this. I would love to go to therapy to help me with a bunch of issues and be a better person/parent but now I have a three week old and breastfeed so I feel like that can't happen for awhile. Please no judgments just looking for some support and advice.

Here's my sweet girl Charlotte