Have you had any diet/exercise changes in the last few months? When I change my diet or go on a weight loss journey my cycle is all off. How about any new stress factors? How are you sleeping? It all effects us and it actually sux
Someone I know had all of their at home tests come back negative and after a month they had blood work done and found out that they were pregnant.
False negatives exist, but it’s more likely just a quirk of your cycle. I would re test but also acknowledge the stress of obsessing over a test can also cause a late period, or stress in general. I’m extremely regular- 28 days like clockwork- and my last period was about 4 days late due to an extreme stressor happening around that time. (4 days late may not be much for everyone but for me it was a major red flag.)