confused

We've been trying for years. And I had surgery back in November and just recently started trying again. This is the second month and I'm a bit confused. I waited to try again till my periods were normal like they were before surgery, and they're clockwork just like before. I have 28 day cycles but usually I start a day or two early. NEVER late. Well I'm now 2 days late but getting bfn...iv never been pregnant. Ever. So idk how long it would take to show positive if I was. Glow doesn't really predict my period correct cause I was tracking my extra bleeding from surgery with it but I know I'm 2 days late based on when I started last month.