i appreciate your query.
If you have a negative HCG
result, then you can be reasonably sure that you are not pregnant.
Its almost impossible to be pregnant with a negative test.
If 18 embryos were formed, some of them might have been frozen.
I advise you to get in touch with your treating infertility
specialist for the next mode of treatment and further course of action for you.
I understand that it is psychologically difficult to go through an IVF cycle and land up with a negative result, but given your HCG result, do not pin false hopes on it anymore
All the best.