Missed period but negative pregnancy test

Alisa

I had my mirena removed on Aug 16th of this year. Started my period on Aug 18th ovulated on 30th or 31st. Today is day 28 from the day I started my period last month....should have started my period today and did not!! 😁 Took a pregnancy test and it was negative. 😢 Could I still be pregnant or could my cycle be changing since my iud removal??? I've always had a regular cycle within the 28 days