Ever since my miscarriage in January I've been finding it very hard to keep track of when my ovulation days are finally got my first period back since my miscarriage in February and from February March I counted 29 days from February period To March period and from March to may period which just went off yesterday I counted 36 days. So I really don't know what to go off of because I am using first response ovulation and in order to use it correctly you have to know your days between but I'm not sure which one to go off of because it went from 29 days in between to 36 days in between