OPKs are so tricky to use... I've been using them for the last couple of months but only got my first true POSITIVE this morning!! For a long time I thought as long as there is a 2nd line, it's a pos - just like HPTs... it's taken me ages to realise the 'darkness' of the 2nd is what counts!!

Have you done the charting course on FF?? It's a time consuming, but it helped me heaps when I first started...