Baby making, Last month my period was 7 days late and now it's here again 17 days later

My husband and I have been trying to conceive for two years. I have had a miscarriage a year and a half ago. I've been tracking my periods and doing an ovulation test kit. Last month my period was 7 days late and now it's here again 17 days later. Ughg. It's so frustrating. Any advice out there? I'm also 39 yrs old and would like to get this happening soon ;). Thank u.