Hi
@Lizzie34 , try not to get too anxious about your readings, they are all good.
Our meters are required to give readings that are accurate to +/- 15% so there is scope for variability in the results. If your actual (true) blood glucose level was say 5.7 mmol then 15% of this would give an allowable range of around +/- 0.8 (I'm doing this in my head ) and all your readings would be within range.
We aren't working with laboratory standard equipment here, unfortunately.