If you feel your air cells are too small then the humidity could be too high. In order for your air cells to grow adequately your eggs need to loose enough moisture. Eggs lose moisture through their shells and the rate of evaporation depends on humidity levels around the eggs. Short term variations in humidity are not important. The average over the incubation period needs to be near optimum to achieve the ideal weight loss. I would try to lower your your humidity I hatch at 45% for day 1-18 then 65% for lockdown. With only being on day 9 this should not be problem as long as you lower it if it is too high. There are some good pictures in the learning centre on candling eggs. Hope this helps and wishing you the very best of luck with your eggs