I've noticed you get all kinds of weird pains during pregnancy Kate -- most of them get put down to progesterone, and if your number is high you'll probably be hurting more unfortunately. The number of times I've read about a yukky symptom (indigestion, cramps, constipation) and "that's because of all the extra progesterone in your body" -- man, progesterone is not a friendly hormone! I hope you start to feel better soon, and I'm sure it's nothing to worry about.
What a surreal feeling it must be Goldie! You're planning a water birth, right?
Lissy, I did literally dozens of HPTs -- my addict advice is to get some cheapo Internet ones (like Oracle) that are less sensitive -- the FRER start plateauing at about 5ish weeks and because the cheapies are less sensitive you can still see the line darkening on those for longer. Or you may not want to continue your obsession and instead behave like a normal rational person (unlike me!).
Thanks for the comments on the scan pic, it was taken at 20 weeks.