Levels not doubling

[Wopies]

At 2 weeks my level was 200 48 hours later they went up to 400-great. But then 7 days later they had only gone up to 489 and the doctor told me that it was unlikely to be viable. I had a scan today and found out it was twins measuring 6weeks 5 days two strong heartbeats but I can't help thinking about the initial levels, especially with twins. I asked the nurse today who said that levels are irrelevant and they just go on scans but everything I read contradicts this.
Has anyone had a successful pregnancy when their levels didn't double? Thanks

I don't have experience of this but when I had my HCG levels checked last week my OB told me not to worry if the levels weren't doubling as successful pregnancies are still a possibility. She said if that were to happen they would continue testing the levels and would keep an eye on things via scans.