Talk to your dad. Mom needs help and it can't wait. She may have postpartum depression. and she needs help. Explain what's been going on and insist that she needs to see her doctor right away. Don't allow him to dismiss or delay it.

Yes, you were absolutely too harsh. After having a baby a woman's hormones are all over the place. You're 15 so you are fully able to order or make something to eat but the worst thing here is your lack of empathy for your mother. Even if she isn't depressed, she is having a difficult time and your reaction is to be rude and dismissive? Someone needs to grow up and it's not your mom. A kind person would be there for a person they love even if they don't understand why they're upset. YTA. Do better!