Toddler tantrums

My daughter is 15 months old & I told her she could have a snack after she had dinner bc she barely had one so I wanted to make sure shes not just eating junk food well she hoes to hit her head off the floor & I pick her up & tell her we just have to have something good for dinner. Shes throwing herself around screaming & I just keep trying to tell her the same thing & that we dont need to act this way & shes still throwing herself around while I'm holding her & hitting her head off me so I set her down & tell her we dont need to act this way & tried asking her things she would want for dinner & she went to hit her head again & just tried to hold her & take her over to the cabinet where we have tub food & told her we just have to have something good to eat first & she still was throwing herself around like there was something really wrong not caring if she was gonna fall or hurt herself so I tried putting her in her saucer bc I was scared I was gonna drop her bc she was really thrashing around & it has a piano thing & she hit her head off that. Is there something I could of done better or should have done? I dont like seeing her hit her head & even me trying to console her wasnt helping it seemed like it made her more aggravated & she wanted to hit herself off me. Thank you for any advice in advance 😓 I'm just at a loss of what to do anymore.