TTC after 2 consecutive M/C's

Now this time we found out we were pregnant 10/03/2016! Over the moon, but how I barely have time to put my feet up never mind legs 😂! So I was 6 weeks when I found out and has a scan scheduled for 6w 4d's mark scan showed only a sack no fetal pole, m.w thought I could be earlier than we thought so had 48hr bloods to see the rise in hcg but they only rose 30% so they were concerned. After another week and half of 48hr bloods they became stagnant. So eventually on 26/03/16 I misscarried. 

We are heartbroken this is our 3rd in total m/c so we have been refared to the recurring miscarriage clinic for some answers. Consultant has told us there's no harm in trying again once the bleeding has stopped (hubby has low sperm count from chemotherapy so we also feel we are ready) 

We've decided to try Using the digital ovulation kits so we can monitor when it happens a lot better. Has anyone any tips for using the opk's as I have never used them before