You and the rest of your family be eed a new Dr., Dr. Phil.

Gastritis doesn't make you vomit repeatedly every time you eat. Occasionally at most. Bad heartburn, etc at other times that typically makes you want to avoid eating.

Your daughter is likely bulimic. If there is a medical explanation, then there is still a mental health/likely ED-related reason that she "enjoys" that illness -- normal people hate gastritis and hate vomiting from it (especially because vomiting from gastritis is usually especially unpleasant because of the raw esophagus).

Frankly, you sound completely insane and I can only assume that your DD's ED is partially a control-related reaction to you. I hope that you at least have good intentions.

You are six different kinds of crazy, OP.

Did the doctor check her for celiac? That can cause repeated vomiting if it's not diagnosed and addressed by switching to a gluten free diet.

She's throwing up and refusing a blood test or physical exam - if not an eating disorder could it be that she's pregnant?