My Period Was Supposed To Start Around Sept. 16. On

My period was supposed to start around Sept. 16. On Sept. 11, I started bleeding a little. I assumed my period was starting early. Now, it's Sept. 30th (19 days later), and I'm still bleeding. It's not really like a typical period for me. It's light enough that I just need a panty liner to get through the day, and I really haven't had any cramping or other symptoms. What's going on?

Some background: I'm 28 years old, about 290 lbs, I'm not on an type of BC, and the last time I had sex was almost a year ago. I have had fairly regular periods most of my life (with a few exceptions - usually when I'm very stressed out). I've been under a lot of stress lately, so I'm wondering if this is just due to stress, or if something more serious could be going on. Also, I've been logging my periods using an app on my phone. Should this go in as a period, or should I just mark it as a note saying I spotted for 19 days?