Hi. Yes. I Had My Third C-section Feb 19th. I

Hi. Yes. I had my third c-section Feb 19th. I recently had intercourse on april 9th. We used a condom as I had just started taking mini pill. And he was looking to get vasectomy. Well I took a pregnancy test yesterday 16th and had a very faint line. Today it's even lighter. Can really almost not see it at all. How long does HCG stay in body. I'm pretty much a weeks and a day out. Could that possobly be it? Or do you think I am pregnant. Thank you