I have no idea what could be wrong with her. A hormonal imbalance maybe?

She definitely needs more tests. However, if a blood test is negative at this late date, she is not pregnant.

Is possible to get two false negatives? If you took two hpts and both are negative could it be possible to have two false readings?

Well, yes. Especially if you tested close together &it was too early. False negatives are semi-common.

A few years ago, my sil had a false pregnancy - only she had a positive on her hpt. She was going to a midwife, but the first time the midwife tried to find the heartbeat, she couldn't. She told my sil that it might just be too early and she could either wait and try again or go to the hospital for a u/s.... She chose to go to the hospital. It turns out she was developing like she was pregnant, having all the symptoms, getting positives on tests and such, but there was no baby. She had to have a medical miscarriage or whatever it's called so she wouldn't continue to go through the pregnancy process. It was so weird.