Plan B postpartum

Ugh I’m freaking out. So I’m 4 weeks postpartum and me and my husband had unprotected sex. I know I know I’m an idiot but things got carried away. He pulled out and I took the morning after pill 8 hours later. The more I read online the more I’m freaking out. I’m 40 pounds overweight right now and I just read that the pill isn’t as effective for overweight women. What are the chances I’m pregnant? If I test in a few weeks will it show positive since I just gave birth?