back to normal

Does anyone know how long after having mirena removed does it take ur body to get back to normal with periods and stuff. I had mine removed on 8/1/16 has a little period for like 4 days on 8/4/16 then went on forever till my next period I though I was never getting a period I finally got it on 9/24/16 and it lasted 6 days so after I got off I keep track of when I'm suppose to start and now I'm 4 days late according to my app. I wanna take a pregnancy test bc my boyfriend doesn't think I could be pregnant he thinks my body just isn't back to normal yet. I did have a some like white milky super thick discharge a few days ago. Idk I'm just confused here