I hate these questions but I want your opinion

I got my Mirena put in mid-November and a week later had a period for 18 days. Two weeks later I bled for about a day and haven't had anymore bleeding since. Is this normal? Because I just had my son in October January was the first time my bf and I had sex again, unprotected. I don't have any symptoms, I'm breastfeeding but should I take a test just to be certain I'm not pregnant? Would you?