Negative FRER at 5dpt Need Advice

Hi! I am 34. My husband and I have been able to get pregnant on our own very easily, however we found out we are carriers for a rare lethal disorder that gave us a 7w miscarriage and a 23 week loss last year. All that to say, we had to do IVF with PGT testing to rule out the gene for our embryos. No underlying fertility issues otherwise. I transferred a 5AA non hatching embryo in Sept that failed to implant (medicated transfer). My second transfer was modified natural and was cancelled due to fluid in my uterus. I have done HSG, hysteroscopy, and biopsy. All look good.

Last week, we transferred a 5AA hatching embryo. I am 5dpt and testing negative on FRER, Wondfo, and Easy@Home. I know people say “5dpt is too early!”… But the FRER is supposed to be so sensitive. It is supposed to pick up 6-10 HCG instead of the standard 25. So, I am feeling discouraged. Has anyone else tested stark negative on 5dpt and still gone on to use a healthy pregnancy? If so, when did your FRER show up?

Thank you!