Underweight toddler

So my little girl has always been super small in like 10th percentile for weight her whole life but very tall like 80th percentile.. the doctors never seemed concerned since she was always hitting her milestones and is a generally happy girl and a great sleeper. She's always hated drinking milk or food since she was a baby.. now that she's a toddler it's continued on. She's now 2 years 3 months and weighs 10.5kg/23lb but is 91cm height.. she is like a stick. She can only wear tights otherwise all her pants fall off 🤦 anyways.. I calculated her BMI this morning out of curiosity and she was a 12 which is like under 1% and seriously underweight. We try everything we can to get calories into her, adding butter and nuts to her oatmeal, giving her ice cream after dinner and she will eat a whole avacados easily.. but she is just a stick no matter what. Should we go to a nutritionist do you think? Is it worth it? Or should I just not worry.. she is doing fine milestone wise except she's not very physical. She can't jump yet or run exceptionally well but she can ride a bike like a pro 🤔