Not putting on weight

My baby hasn’t put on ANY weight since her 1st birthday! She has grown over 10 cms in height and 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)? She’s 20 months old. 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 !!!