2 chemicals in a row

Little bit of a back story, I have two children 5 and 7. I am not with their father anymore. I never had any trouble getting pregnant or staying pregnant with them. I was on the pill and decided to go off both times, first pregnancy took 8 months of trying and second time got pregnant right away. Now, I am with my new partner and we are trying for a baby. I am O- and he believes he is O+. I went off the pill 3 months ago, and got pregnant right away which ended with a chemical pregnancy. I had 2 very short irregular cycles after that, 3 days long and 17 days apart, and then got pregnant again. I just found out 6 days ago, and my tests never got darker. Doctor sent me for blood work Thursday my HCG came back at 7, and last night I started bleeding so I’m currently having another chemical pregnancy. Has anyone been through something like this before? Anyone else O- and having trouble ? Please any experience or advice would be helpful. I’m devastated and heartbroken my body keeps failing us.