Please bear in mind that no screening method can ever be 100% accurate and there will always be false positives and false negatives. A good screening service could have as many as 5% of people without sight-threatening retinopathy mis-identified as having it. Screening results should never be considered as a 'diagnosis' but an indication of whether or not further tests are needed by an ophthalmologist.
As the aim of diabetic eye screening is to detect sight-threatening diabetic retinopathy. The standards for minimising false positives do not apply to the detection of background retinopathy and the percentage of people falsely identified as having BDR is likely to be much higher. There are a number of features that can be confused with diabetic retinopathy such as areas of pigment, unusual appearance of vessels or retinal haemorrhages occurring for another reason which is not diabetes. The more screenings someone has, the more possible it is to identify confounders for diabetic retinopathy so someone can go from 'background retinopathy' to 'no diabetic retinopathy' even if there has been no visible change.
Background retinopathy generally takes at least 5 years to develop. In people with type 1, where onset of diabetes is identified very rapidly, it is very unlikely for background retinopathy to be present at the first yearly screening. (This is unlike type 2 diabetes where people may have had diabetes for several years before they are diagnosed so a good proportion of them have diabetic retinopathy at their first screening.) If you are genuinely type 1, I would treat your result with some skepticism.
In any case, background retinopathy does not affect your sight and the risk of progression to sight-threatening retinopathy is much reduced by maintaining good diabetic control.