Opk tests- have they worked for you?

Sarah
Hi,
​I'm considering trying opk's.
​A friend was using some ebay cheapie ones back in 2011 and kept moaning that she never got a positive. There was a reason for that...she was already pregnant! So she donated them to me and I tested in the next cycle. I never got a positive OPK but that cycle I fell pregnant. I was devastated when it ended in miscarriage at 8 weeks.
​I've suffered another miscarriage this march and am ttc. Has anyone had any luck with opk's? How accurate are they?
​Rainbow baby dust to you all!