Late period, positive at home test

Alyssa

So my January period was 2 weeks late if what it should have been, it came on January 18th and ended on the 22nd. It wasn’t very heavy but it wasn’t too light to think it was a period. My period for February was late(basing off possibility getting it on the 18th). 3 days later I got a positive at home test! I took a first response test and the pink lines came up so fast and were very dark! I think I’m 5 weeks pregnant. March 1st I go for my first OB appointment and I’m just curious is there an possibility I could’ve been pregnant in January? Has anyone ever had what they thought was like a normal period while pregnant? I’m just wondering if anyone else has experienced this. I’m thinking at my appointment I maybe farther along than 5 weeks.