Im 13 and feel underpaid for babysitting?

So im 13 and have only babysitted for one family before. So they have 2 kids one is 10 the other 6. They act so wild. They com over my house. But anyways like i dont tell them what to pay me they just give it too me. I am very responsible and babysit alone. But i usally babysit from 8am till 5pm and they only give me 20 dollars. When my mom had babysitters come over for me she would always pay like 150 dollars for only like 3 hours. I need the money but i feel underpaid for everything i do. I clean up there messes take them to the park and give them toys and feed them really good healthy food....what do i do cause i need the money. Is there any way i can earn money another way. Btw im a girl