Growth issues

Hi mamas. I got a question. Maybe others have experience with this. Im struggling because we all at one point worry about our children's growth. Especially before growth spurts.

My concern is the growth spurt hasent come... for months. My child has slowly fallen off the curve since 6 months. 14m old now. In 1st percentile for height when she started in the 80th. She hasent sprouted. For months. Weight starting in the 70th percentile is now in the teens. With not much progress even with her eating more than her 3yo sister. We upped her calories, fat. Etc. Nursing as much as she wants. She is active and healthy crazy 14mo. But im worried. How the heck isnt she growing? She does have an upper lip tie that makes especially sippies a challenge.its hard to get pediasure into her. We have a revision coming up so that should help. She hated toddler formula.

They want us to wait until after the lip tie revision and until she is 18m and continued decreased growth before they refer us to an endocrinologist? That feels so far away. Should we be pursuing the referral earlier? Can a lip tie effect height as well as weight?

Im a worried mama.