Lily, I feel desperately sorry for you. Far, far too close to home for a double whammy baby bomb. Do confide in your sister, it will lessen the sting of her news by 70%, I promise 
Beans, I'm so chuffed you have a date! You're moving forward!
DizzyN, studies have been conducted which compared the efficacy of temping in pinpointing ovulation when compared to the findings of ultrasound scans.
Temping theories work on the premise that ovulation will occur on the day of the temperature nadir (lowest point) immediately prior to a succession of three higher sustained temps.
However, when US scans were used to pinpoint ov, the nadir-temp theory was only supported by ultrasound confirmation 34% of the time. The bad news is that reliability of opks came out with a relatively low score too.
This is why fertility specialists urge us to throw away the opks and basal body thermometers and just have regular intercourse every 3 days or so throughout the month. Every month. For fucking years.
But those thundercunts can go and swivel, right?