32 and TTC #6 possible implantation bleeding but AF only 3 days late

Been trying since having IUD removed 1/5/15 AF regular 29 day cycle each month exclude April, might have MC cycle was late, still trying but being that cycle was late I calculate ovulation days for both 29 day cycle and possible 32 days had sex both suspected Ovulation days went to doctor 5/19 urine and blood negative so now I wonder if I tested too early and whether I could possible be pregnant any insist is helpful been praying for my last one....