Since your cycles are irregular, use an opk (ovulation prediction kit), you can get them pretty cheap at most stores. Vitex berry and red raspberry leaf can help regulate cycles.
hi, i dont know if you have heard of DUO FERTILITY Advanced fertility Monitor. its a small sophisticated ovulation device. accurate especially for women with irregular cycle length like you and i . its a bit expensive. i got it for £500. it's very worth every penny, trust me, and you get your money back after a year of ttc without luck.
go online and research it.
best of luck.