Random bleeding

Vi

So I’ve been on the implant birth control for a couple months and I’m always late on my periods. I also bleed dark blood like leftover from the last period. I don’t know what to do. This has happened for months even before the implant. I use to take pills instead but I would also for get to take them or double up on them if I forgot. My doctor says it’s normal. I’m stressed from work.

I just don’t know what to do anymore.