My son may have galactosemia, but the tests are not sure...?

My son was born 11.15, and the tests for galactosemia show that the enzyme to metabolize galactose is well within range (it has to be greater than 40 mg, and it is 270 mg), but the galactose is still out of range (it has to be less than 15 mg, and it 15.5 mg). What could be the meaning of this? I am very scared of what his life could be only because no one in my family or my fiance's family has a metabolic disorder, and neither does my eldest son (2 yo). Is it the tests or what? Also - before this was known, he was on milk-based formula. In fact, he was put on it from day 1, and was on it for a week. He showed no signs of complications (fatigue, jaundice, weight loss). He actually gained a pound in 1 week. He seems to be doing fine, I just am very overwhelmed - I am not sure if it was me or not. Please help in any way you can.