Secondary Infertility

Hi Dr Sher
I recently completed my first cycle of IVF in Australia and both FET failed. The first one in Feb was a chemical pregnancy, and the second one last month did not even detect any hcg in my blood.
I have secondary infertility, conceived my first bub 6 years ago without trying and no issues. She was born at 37 weeks/
I have completed all necessary bloods, ultrasounds, etc and nothing has come up. Been told by my FS that everything is normal.
My twin sis was on clexane and her FET worked. I asked my FS about clexane and she won’t prescribe as she feels I don’t need it.
Are there more tests I can do before we start our second cycle? Or is there any general advice you would offer? Thank you