Immunity is a natural process which evoles with growing age and not always innate. Child's exposure to outside world practically begins after 2yrs of age. Mild frequent infections may deter parents. As long they aren't life threatening it should b accepted with a pinch if salt.
Next Steps
Get her immunisation schedule updated and maintain balanced diet.
Health Tips
Plot her on a Growth chart and monitor her growth. If as expected then it isn't a matter of concern.