Hi Mooshie,
After losing our baby last May I decided after 2 cycles ttc to use OPK's.
I used Fortel for 2 cycles and I never got a true positive. So, I started to think I wasn't ovulating. Bloods confirmed I was however.

Like you I found the supermarkets a bit too costly. I then decided to purchase on line from Lullaby Conceptions. Once again I didn't get a true positive - I phoned Lullaby and Jody (owner) explained some women just don't but they still ovulate. She suggested I start to bd - I did and I conceived! I researched at great length the whole opk thing. The LH surge as I am sure you know occurs 12 - 48 hours before ovulation and it is the lutenising hormone that signals the release of the egg. This surge isn't easily detected in some womens urine. I found that if I tested twice a day (for me it was 2pm and 6pm) I got a much darker line but still not a positive. Sadly I lost the pregnancy above at 5 and a bit weeks. I used opk's in the next cycle and conceived immediately. However, I lost that baby recently too. So, like you I am going to be using opk's again soon.

One thing I found with Lullaby is that you don't get any second line unless you are about to surge. It is worth even giving the company a call and talk about it with Jody who is amazingly compassionate and informative. I know that it is universally said that the line HAS to be as dark as or equal to the control line to be positive however I have NEVER got a true positive. There are lots and lots of stories similar to mine, so just keep that in mind. I bd as soon as I see a second line for 3 nights. I have been fortunate to conceive on every occassion I have done that. The other thing that I also used was preseed. I used this because I don't notice EWCM since having children. There are lots of success stories using this also. Anyway just remember to bd as soon as you see a second line and once you see a second line test again 4 hours later (make sure you limit your fluid intake for a few hours prior to testing) and you may get a darker line. Once I tested at 12 and got a feint line 2pm slightly darker, 6pm slightly darker and 8pm gone altogether. But I conceived then. So, the moral of the story is every woman's body is different and the absence of a positive line doesn't mean that you are not ovulating. I highly highly recommend though that you begin the bd as soon as you see a second line if you chooose Lullaby.

Good luck Mooshie, maybe we will be Belly Buddies hey?
love and blessings,
Deb