Worry about my child weight

Hi mummies, do anyone has the same problem? My child just turn one but her weight doesn’t seems to gain. Though she more to the smaller percentile range since birth. But I cannot help worry. She neither picky eater nor less eater. Her formula intake normal although she quite active.. any suggestions? On the side note, isit normal if she’s teething, with lots of saliva but no teeth to appear yet #worrymommy #advisepls