Nexplanon Implant

Okay so I've been using this form of birth control I would say for about 5 months now. So at first I didn't really get my period at all. Then my periods started to become really light and they would go away for about a day and then be relatively light for a few weeks, which was scary because I felt like I was never off my period, and now for the past 3 days ive been having the most heaviest bleeding ever. I am so confused with what's happening? Has anyone experienced similar or knows what going on? I feel like my body is trying to get used to it, but it is irking me to not know when I will be on my period and off.