Vaginal Swabs

Does anyone know if vaginal swabs can be done wrong? I did the swab, but then wasn’t sure if I did it right, so I put the same swab back in and did it again just to make sure.. that shouldn’t have messed up what shows on the swab right? Also, is it possible to not swab right to get a proper sample? Mildly freaking out about my results being inaccurate as it seems like I have an infection, but none was detected!