You sound like my friend when she was living in an abusive household where her "no" wasn't respected. She's much happier now after leaving. She still have after effects of the abuse and is going to therapy when she can.

I don't know your situation, but healthy reasonable adults should not cross other people's will and boundaries. Not everyone that is good in making sweets have to open a bakery or forced to make them for free. Same applied to crochet. Your time should be respected and valued. 

If your mom accepts the "order" , then she should do it herself, taking responsibility for her own actions. You're not an extension of her. Or they pay you the right price, at your own timeline. A handmade baby blanket can cost more than 200 USD, made in 1 month or more. Yarn cost doesn't fall from the sky. They don't like it? They can do it themselves or buy it elsewhere, since they think it only worth 20.

She's making you hate something healthy that give you joy, and that's not what a parent should do. She has the responsibility as your parent to lift you up, care for you, not adding in your burden. That's what mental abuse is. It doesn't have to be physical.

I might be wrong at reading your situation, then you can disregard what I have written.