12dpo bfn

Hi ladies need to vent bfn 12 dpo been trying 3 month after 2 misscarriages. I just feel so low and don’t understand as why I’m not pregnant. I feel like screaming. Why is it so hard. Dtd Up to ovulation, day of and after. So why now bfp. I just feel like a failure. I’m 35 and feel like time is running out. Please help x