Help! (TW pregnancy loss)

Hi all, Wondering if anyone could help or had any experience with a chemical pregnancy. I got a very faint positive last week on 8dpo, it kept getting darker up until 13dpo, where it went lighter. On Monday, 14dpo (due to start my period) the line was pretty much non existent so I’m guessing I have had a chemical pregnancy. I took an ovulation test today as I want to track when I ovulate again and it was very very dark, almost positive but I have today started bleeding. Any ideas why I would get an almost positive ovulation test if I have started bleeding? Thanks guys!