I'm sorry you're having to go through this. I'd say mark on your calendar every time you start and finish your period. Then count the days in between every cycle. Average out those numbers and then enter that info into an online ovulation calculator and try on the days it tells you to.
So lets say one month you go 28 days in between periods, the next 31 days, the next 29 days, etc. Add em all up and divide by the number of months you calculated for to get an average number of days between each period. That's what i did since mine were slightly irregular as well. Best wishes and I hope you can get pregnant soon!!
I would definitely say try getting a ovulation prediction kits or a fertility monitor... These will give you the best idea of when you are ovulating =) I am so sorry to hear about your loss for the second time =S Keep strong! (((HUGS)))