I'd wait a week and test again. Sometimes it takes a bit for your body to register the hormones. The discharge you are explaining can be mid cycle breakthrough (sometimes happens no worries), or implantation discharge (not hugely common, but it happens, most women miss it lol). Like I said wait a few days. If no cycle, test. If negative, wait like a week. Still no cycle? Call your ob. Sometimes you need a blood test, not everyone pops their bfp with the urine tests (that is uncommon though)
By "af" do you mean period? Well that's what I'm assuming, lol
It doesn't sound like you are pregnant, the brown discharge sounds like dried up blood so you might actually have some blood clotting, I would definitely recommend seeing your gyno about this though. Not just to find out if your pregnant but to also see whats going on down there.
Good luck, I'm sure everythings fine.