Hi. I Know This May Be A Silly Query But

Hi. I know this may be a silly query but my period is not due until the 23rd of September and I took a pregnancy test the 15th and it came back with a very faint line so I did a digital one the next day and it came back positive with 1-2 weeks. I booked to go to the doctor on Friday the 18th and his test came back negative. 2 hours after I left the doctors I took another digital one and it appeared pregnant 2-3 weeks and I also did a clear blue plus one and it came back positive. I then took another test on the 19th and it was pregnant 2-3 weeks? Am I pregnant if so why didn't the doctors test come up positive? Could 5 pregnancy tests be wrong?