Arm implant = no period?

Harley

I got the arm implant on the 17th of April this year, and I'm now 18 days late in starting my period, is that normal? I was taking the pill before that and had no problem. I'm almost never late to start (and if I am it's usually only a day early or late) and I've never missed one before so this is really unusual for me. Any feedback is appreciated.