Meters have a 20% error. usually 2 reading so close together (248 and 5 minutes later 117) means the finger was contaminated... DId you wash and dry with a CLEAN towel?
ask for a OGTT (oral glucose tolerance test) they give you a glucose drink and test your BG every 15 or 20 minutes for 2 or 3 hours. that will give you the best info on how well your body processes carbs. With an A1c of 5.5 your in the Pre-diabetes camp. Many of us dont beleave in pre-diabetes, we think your diabetic and your pancreas still works a little.
you are 29 so diabetes not likely. usually happen when you 45 or older. 5.5 a1c is also not diabetic or even pre diabetic. most likely meter is broken. lab result showed normal sugar so i think that is right