Advice: really hoping for the best!

anyone test 3 days before their period was due and got a bfn but later have a BFP? I've been having all the early preggo symptoms and I know they're not in my head cause these sore boobs and crying at EVERYTHING are no joke. my last period was feb 8. and I ovulated on Feb. 19, had sex on that day we didn't pull out or use any protection(we've been doing it like that since). AF is due in 3 days and I keep getting bfn but I have a feeling my HGC levels are just too low even for the FRER test. I am a tiny thing so maybe my body takes longer to produce enough to show up. what are your thoughts ladies??