19 months and not walking

Help! Very worried mum here, my little boy has been crawling since he was about 10 months, then he started knee walking and now he is almost 19 months and still doesn’t walk, he will sofa cruise, take a few steps on his own but then just drops to his knees…I have taken him to the GP she said to leave him for a month but im so worried!!

also the comments you get from other people/family members do not help!!