Hi Kirsty,
Your OPK results sound totally normal to me. You have only recorded 1 positive on one day, the rest of your results are the start and end of the LH surge. I got almost the exact same results as you this month and last. I would guess you Oed on the day after you saw the positve (just) result and the day you Oed the LH was still a bit detectable, hence 2 lines. Remember that 2 lines is still negative if the test line is lighter than the control line. Some people get a faint 2nd line throughout their cycles. What's important to note is when you see a proper positive.
As I said, sounds normal to me.
Good luck. I think we will be due to test around the same time!!