Dark lines?

This is probably stupid but...today is the first day of my missed period. I’ve known I was pregnant since Friday when I got a ridiculously faint line. Now my line is very bold. It’s bolder than it ever was throughout my entire previous pregnancy. I had a healthy baby two days before his due date. I am a little concerned about a molar pregnancy. I have no history of any pregnancy complications or miscarriage, but I can’t help but worry. I know some people say dark lines=twins but I don’t think that’s been substantiated. Have you guys had very dark lines on day of missed AF and everything was fine? I know what day I ovulated because I used opks and bbt. I work in medicine so of course I am the one that takes something that other women would be delighted about and turn it bad lol.