Hi, Had a baby 4 months ago and i'm 5weeks pregnant. Risks...? Has anyone ever known anyone 2 get pregnant....?

Hello I had a baby Oct.28. I was on the pill took it everyday and I still got pregnant. I'm 5 weeks and my husband and myself are stoked we wanted more kids but this is early. Anyone ever heard of anyone having a baby so soon. I can't find anything online. Thanks ladys.