6 month old won’t drink her bottle!

Br

My daughter is 6 months old (7 months in two weeks) and since I started giving her solid foods she WILL NOT take her bottle anymore. She fights and fusses and when she finally drinks some she never finishes it. She used to finish a 5oz bottle at every feeding and now she’ll drink 2-3oz... I know she’s hungry because a she’ll eat cereal or fruit/veggies no problem! We had an appointment yesterday for her 6 month shots and they were concerned about her not gaining weight and her dropping into the 9% from 34%. I told the nurse she won’t drink her bottle since starting solids but she just laughed it off like “oh, babies, they’re so stubborn sometimes!”. My doctor did the same exact thing at her 6 month checkup!!!! They told me to come back in a month to make sure she’s still gaining weight but they don’t seem concerned with WHY she’s not!!!! I’m so frustrated and don’t know what to do. :( What can I do to get her to drink again?