I don’t know what to think

Mid March I had unprotected sex my whole fertile week, on my ovulation day, and the few days after. Fast forward to after the two week wait my period was late. I took a test at 18dpo and it was positive. But I got my period a few days later and just figured it was a false positive. Ever since my periods have been 3-4 days of bleeding. I just don’t know what to think. I know when my mom was pregnant with my brother she had her period and didn’t even know until she was like 5 months along. I’m wondering if it’s possible to still be pregnant since I still have other symptoms. Has anyone else ever experienced this and still ended up being pregnant?