HCG levels..?

Sooo not last Tuesday but the Tuesday before i took a pregnancy test it was pure negative. 9 days later last Thursday I took another test and it was crazy positive. Like test line darker than control line. I got levels checked Friday and I got them back today. Levels are range 1100 and progesterone is 13.5. So they put me as “5 weeks” but how could I be 5 weeks if I got a negative the week before. Am I just 4 weeks with high HCG?