Baby not growing since 6 month appointment

I'm freaking out just a little bit and getting a little frustrated with the ped's office. At her 6-month appointment, my daughter was 27 inches. I have measured her several times over the last four months including just a few minutes ago, and she is still exactly 27in. I have had to reschedule her nine-month appointment twice now and thanks to covid-19, it is now been pushed all of the way out to the middle of August where she will be 11 months. Has anyone else ever had a baby that didn't grow in length for several months at a time? This puts her in the 12th percentile when she was born in the 99th and spent her first six months around the 50th. She started refusing breast milk and formula at 8 months and I worry that she may legitimately be malnourished.