False negative pregnancy test how to correctly use it?

I'm new to this but would like to talk to someone who is going through kinda the same thing. I was depo for 9 months but my last shot was February 2021 and I hat a light period in September 2021 but nothing in-between and nothing since then. My husband and I are trying for a baby so I went to a infertility doctor 2 months ago and found out I have pcos and my insulin levels are higher yhan they should be so I've been put on medicine since then to help with levels. We've had lots of sex about 3-4 weeks ago and this past week I haven't felt like my self so I took 6 pregnancy test from 3 different brands and they all came up faintly positive and this morning it was a Lil darker of a positive then the last 5, I called the doctor asked for a blood hcg test because of all the positive test and the blood test came back negative..... I was told that all the pregnancy test were false positives, 'which if they came out of the same box I would under stand but it was 3 different boxes and I bought them 2 days apart from each other from different stores'. I really need some advice because I bawled when I was told the blood test was negative I've been doing everything I've needed to do. #pcos #tryingtogetpregnant #needadviceplease

Has anyone else had a negative pregnancy test but three came back positive how common are false Negatives?