Hey Miss J,
Hope you're ok,
Try not to worry you might be ok but I have said before that it would be well worth getting a CD21 test done.
CD21 tests for Progesterone where as the OPKs test for LH the hormone that surges prior to OV.
Speak to the docs and they will advise you when in your cycle you will need the test, I have mine on CD 31 of a 38 day cycle.
You would need to have yours either 7 days after your LH surge (Positive OPK) or 7 days before the end of your usual cycle.
I know that may be difficult to pinpoint so your doctor may do what mine did and do 2 or 3 tests to try and get the correct reading.
I know you might not want to go down this route but I think it will be better for you to know where you stand rather than the heartache of BFNs all the time.
If you're not OVing you can fix things easily with different hormone tablets so don't worry if that does end up being the case.
Keep on doing the OPK as you never know your surge may still be to come, I have the same OPKs and my surge is as dark as the control line if that helps, I'll put you a pic on tomorrow and I should have a negative one to show you then too as my surge should be over then.
xx