I'm still on my period??!

This is the weirdest cycle ever. My husband and I were ttc and I was so excited because I was 2 weeks late on my period. I for sure thought I was pregnant but every test came back negative 😞. Then I started my period so I knew for sure I wasn't pregnant but I've been on my period now for 14 days and counting which my period normally lasts only 7-8 days. It's also a very heavy flow. Any one else experienced this? I'm not in pain or anything just won't stop bleeding. At what point should I call a doctor? Thanks