Asking for answers as two of my docs have none

My baby hasn’t put on ANY weight since her 1st birthday! She’s 20 months old now. She has grown over 10 cms in height and is in the high 90s for height percentile though and is active, smart and very talkative so that way she is healthy (n infact ahead with her verbal skills n height areas). But is it okay for her to not increase weight (though everything else is on track or if not ahead)? Two of my Docs seems puzzled , what do ur docs say about this? Pls help this mommy with answers as I haven’t got any satisfactory ones from the docs I went to !!!

(She started at the top of the charts To now right at the bottom -8lbs at birth-a big Baby! 19.1lbs at 1year and only 19.6lbs at 18months- which was our last check up. I’m told she should be ATLEAST 24 lbs by now ideally 28-29lbs but shes no where near!!She is 20 months now but I haven’t had a weight in n she doesn’t seem to have put on any weight infact seems thinner. I’m medium built and my husband is tall and lanky. Could it be his genes kicking in this early in her or lack of high calorie food? I give her home cooked meals and she does eat sizeable amounts. Both the docs I went to seems confused as to why she hasn’t been putting on weight AT ALL !!) HELP!