So discouraged 😔

12 DPO...thought I had tons of symptoms this month, but I started having light brown spotting today (only when I wipe). I don’t usually have spotting, but I figure that means AF is coming. I literally don’t understand. I have perfectly regular cycles and get a strong OPK midway through my cycle every month. We BD often. This will have been month 3 trying. I’ve read over 60% of couples conceive within 3 months. Husband and I are both young and healthy. Is it likely one or both of us has an underlying issue? I went to my ob last week and she said everything looked great, but I just don’t know. I’ve been scared of infertility (for no specific reason) for years, and every month that passes makes me think that could be in my future.