Weird smell

Came home from college in May. my bf and I of course had some "hey we need to make up for lost time for like a week" sex and then I had my period. After that we had sex again and I noticed a fishy smell during. I made sure to shower afterwards thinking it was a buildup of sweat and whatnot. The day after, I didn't smell it anymore. I realized a couple days later that the smell only showed up while we were having sex. so it has to be BV right? I figured that's what it was and first decided to see if it cleared up on its own considering I wasn't itching or burning. Well it never went away. The only thing that's ever changed is his body wash. I even stopped my birth control for a month to see if that was contributing but nothing changed. Could the soap be causing the smell? I tried to call my doctor for an appointment but the earliest she's available is October for whatever strange reason. What do I do?