Late period, negative pregnancy test

Hi all,

I had been on the birth control pill for 15 years. We are now trying to conceive. I stopped taking the pill after finishing my last pack. I was on a 28 day cycle, finished the pills, had my normal period and followed the <a href="https://play.google.com/store/apps/details?id=com.glow.android">ovulation tracker</a> on Glow. We were intimate almost every day of my predicted ovulation period and on the day I should have ovulated. My period was supposed to start Monday (it’s Wednesday) and it still hasn’t. I took a Clear Blue Digital year Monday night (around 10PM) and it was negative. Is there a possibility I might be pregnant even though it showed negative? Or is my period off since I had been on birth control pills so long? I’m confused about what’s going on. I plan to take another test Friday AM if still nothing. Curious if this has happened to anyone else and what the result was. I’m trying not to get my hopes up, but also want to know what’s going on.