dobby FX for you that it's just a bit of spotting and nothing else. Glad you got to speak to someone.
Mummy so sorry to hear your news 
Looking Due dates: it doesn't matter whether the doc works it out from LMP or Ovulation/Conception date or length of your "blob" on the scan, they still give you a number that's equivalent to weeks from your LMP (I.e. 2 weeks older than actual conception - you are 2 weeks pregnant the day you DTD successfully!)
For example, say your LMP was 6th April, that makes it 7+0 today. Imagine you don't track ovulation, but you actually ovulated on Day 18 of your cycle (not day 14 as universally assumed by all medical processes). This means you ovulated on April 24th and today are 6+3. When you go for your 12 week scan they will measure your bean and work out what that length equates to for the average foetus. You might get given an estimated EDD based on a calculated conception of April 22nd for example.
So if the doc calculates your EDD based on your LMP, you get 11 Jan. Based on actual ovulation/conception (if you knew it), your EDD is 16 Jan. Based on your 12 week scan your EDD is 14 Jan. the only thing you can be sure of, is that there's a baby due some time in Jan! I think they take the date from the scan as being the most accurate.
Hope that helps