Fixing the period tracker

I got the implant on the 9th and I haven't had my period. I'm not going to. It's saying I'm 20 days late which sure is accurate but it keeps asking me if I've started my period yet. I'm not going to have my period for 3+ years is there anyway of fixing that? I've already set my birth control method as the implant in the app and put the date I got it too. I love using this app though so I don't want to stop but it's annoying.