Had to switch bc and now my period is gone...

Elizabeth
Hey ladies,
I had mirena for about a year and a few months and then it decided to pop out after lots of cramping and bleeding. Afterwards I got on Lo loestrin fe and have been on it for about 2.5 months. I had one period and since then nothing. I've taken some pregnancy tests and all are negative. All of my ovulation tests come out positive for the past few weeks. Could I be pregnant? Why is my period suddenly MIA? 
The reason I ask is because I have been on Lo loestrin fe before and I had a regular period every month. Now nothing. Thoughts?