Late AF, BFN

Am
Hi Ladies! I have been TTC for 3 months with cycles ranging from 30-34 days. I had many pregnancy symptoms a week ago but those has faded. I have sporadic nausea and mild cramps. I also feel like my abs are sore. Now I am on day 36 with no AF and BFN. I am very confused because so many are able to get their BFP before their missed period. Any thoughts/advice/stories or encouragement would be appreciated. I don't know when it is a missed period vs late positive.