My 7 year old SWCAH daughter is on 10mg of hydrocortisone per day and .05mg (half tablet) fludro per day.  Signs of oversuppression are moon face (very round and chubby face), slowing down of growth (height/length), and obviously results of blood tests.  My daughter’s doctor calculates her meds based on the blood tests results and her height (in relation to her chart and making sure there has been no sudden increase or decrease in her percentile).