confused!

So I just want to know how many other mommies experienced this. Back in May I got the IUD mirena it was going good up until sept. I began to get a sharp pain so I had it removed. Right as soon as it was removed I began to bleed for a week like a normal period. is it considered a period? I haven't had a period since then and I continued to get negative test. Well a week ago I got my first positive test. My question is, how many mommies went through this? how far along were you on the ultrasound? could I still be a few weeks pregnant counting from my last period oflr is it possible I be less and just missed periods?!