If your doctor's H. pylori test came back with different results to ours, it's because the tests are different, with different levels of sensitivity.
There are many different methods of detecting H. pylori. The method our lab partner uses is the DiaSorin LIAISON® Meridian SA Automated CLIA assay. It's been shown to be an accurate and sensitive method of detection in the stool.
There's literature to support this, and it isn't uncommon to have different results for testing when different methods are applied, due to the varying sensitivities of testing methods.
Biopsy of the stomach wall is generally the most accurate way of detecting H. pylori, although this is quite invasive and rarely used.
If you want to retest for H. pylori with us, it's likely that the results will be the same as last time—different to your doctor's—due to the differing methods of analysis.
If you show your doctor your results from us, and explain the above, this will allow your doctor to treat you in the best way.