Help!?

Me and my significant other had intercourse on the 17th. According to Glow, my menstrual cycle is to begin on Nov 2nd. Yesterday, I noticed slight bleeding. Today, also slight bleeding. Not enough to warrant a pad but enough to have a panty liner. (One, would be more than enough. I'm just very cleanly, so I change often.) I'm not sure if Glow is wrong, my period is being weird, implantation bleeding or just too early to really tell. I'm 23, so I've never been in this position before. Any advice would be great!