Old blood, no fresh blood

I skipped my last period deliberately by taking my pill packets back to back. It's the first time I've done that but there were no issues that week I was supposed to bleed.

So now I've come to the end of the second packet, and my period/withdrawal bleed started on Tuesday night. However all I'm getting is a very light amount of old blood. There's been no fresh red blood at all. It's now Thursday morning and I'm a little concerned about that. My periods are light usually anyway, but it's not even touching a pad, it's that light.

Has anyone the else found this happen? Is there a chance this could be a sign of pregnancy at all? We don't use any other form of protection. It's not a bad thing if I am pregnant, just curious!