Ok still no BFP 🙍🏽

Im starting to get discourage..like its the end of the Oct. Month..well close to it i have not seen AF since Sept.2 it was her last day..i went to docz p-test came bck BFN(OCT 4,8,11) ..& ultrasound (Oct11) was nothing..doc said i was fine healthy..🙎🏽i have been having bck pain..and frequent urination..and gas..& one sided pain..is it possible i am preg just to early for baby to show on ultrasound..?...idk im so confused..