Ivf Week 5 & taken off meds with hcg at 991

My wife & I had two blastocyst donated egg embryos transfered on day 5, 13 days later (and showing many symptoms) her HCG level was 640. Three days later (at a different lab) it dropped to 530, but then went to 991 two days after that. However, the nurse or the lab misinterpreted the 991 and told us that the hcg level went negative and therefore the Dr told us to stop taking meds since the pregnancy was failing. The next week we went away and she went into a hot tub where she started having pains then later that night bled all over. When we returned to the Dr two weeks later her Hcg was 450, and another Dr told us that there was a mistake, that her third hcg was actually 991 not negative as we were told. The first Dr now says that either way it would have been a failed pregnancy since 991 on week 5 with ivf is too low. Is this correct? Or is it possible that she initially had twins , and one stopped developing, but when we stopped taking meds & went into the hot tub, that caused the second to fail? Or are we crazy to think that had we known it was 991, continued meds & took proper precautions that this could have been a sucessful pregnancy?