BFP 11 days post IUI, 12.5 days post hcg 250mcg trigger

Kristin • Two boys and two miscarriages, pregnant and due in May! 🌈
Is there any way the hCG shot is still in my system 12.5 days later? Dose was 250 mcg. I read that that low of a dose should be out if my system after 7 days. It's not a super dark positive, but it's definitely positive. Trying not to get my hopes up too much but I'm having pregnancy symptoms. I was supposed to test this Friday, but caved and did it today.