Pregnancy with mirena

I've had a mirena in for 4 months. Was feeling abit off so tested yesterday and got a positive. Another today came up positive too. Afew hours later I started spotting, very light pink and only lasted afew hrs. Didn't even warrant a panty liner.

I will be booking a doc appt for tomorrow to get an ultrasound but wondered if anyone else has experienced similar and whether I should expect to start bleeding soon...

Kinda freaking out here since I didn't want any more kids but I really don't want to have another miscarriage (I've had 4) nor do I want to be told by my doc that I have to terminate again (had to terminate my last pregnancy due to needing treatment for cervical cancer)