My toddler self harms😢

My daughter is 20months and as to be expected she throws tantrums but lately I've noticed after the tantrum she still pretty upset and she scratches her leg and scratches and scratches and scratches until there's a huge chunks of skin missing and she's bleeding. She also pulls het hair, and starting fro hit. Or she'll flat out ignore my requests all together. I'm trying to be patient, but my limits are being tested. Im a single mother, Idk what to do anymore. It overwhelming