How do I get my cycles regular?

I don’t have PCOS, all my blood work has come back fine on the ultrasound showed that I don’t have anything wrong with my uterus except that it’s tilted. The thing is is that my periods for the past year and a half especially recently have been very irregular when I do have two consecutive periods that quite short in time and then I have one for about 40 days. There is no pattern to it and I tried using opk’s and saw that I did have a side around day 14 but I never got the peak I just got the flashing :-). How do I get my cycles the more regular?