Positive test 5 days after termination ?

So five days ago I got a surgical termination for many reasons e.g: too young, no money, not a stable home life. Anyways I just took a pregnancy test to make sure I wasn’t pregnant but the test came up positive straight away and really dark. I was only 7 weeks and 5 days when I had the termination. And I know HCG hormone stays in your system a little bit afterwards but when does it start to go away ? Why was my test so dark and positive straight away? Is this normal ?

I got the rod put in while I was sedated could this have anything to do with it ?