I caught an STD but was a virgin and my bf doesn't have it

Very personal to share but last month I found out I have chlamydia. I lost my virginity at 22. I have never done anything sexually with anyone beside my current bf (except once I rubbed on someone but my undies were on a couple months before). I've never even given oral before. I am pretty new at everything. I found out during my first Pap smear at the gyno last month. I was told I have chlamydia and was prescribed Azithromycin. I took the meds and it's easily curable apparently. I get rechecked in a couple days. My bf got tested finally recently and tested back totally clean for all types of STDs (I went with him and saw screenshots of the results and I don't think he's lying). He didn't even have chlamydia. If I apparently have it, how did I not give it to him. We used to have sex all the time without a condom but started finally using them after i found out last month. I'm just concerned how I could've gotten it. Maybe there was a mistake somewhere down the line. Maybe I  had a false positive or he had a false negative? That's possible right? Uggh I'm so scared and sad. I don't want people to think less of me. I have only been with one man like that and now he can't even trust me...