Waiting for Period to start back up PP

Jae
I am 4 months PP and got an IUD (Mirena) at 10 weeks PP. I've had spotting a few times a week ever since, but nothing I feel I can classify as a period. The last few weeks, the few days of spotting were heavy enough that I needed a light tampon, but then it all stopped after 24/36 hours. 
I've had to reschedule the IUD check with my midwife twice because of health issues my son has been having, so I haven't had the chance to talk this over with her yet.
For everyone who got Mirena PP, what have your experiences been?