What Causes Irregularities In Periods?

Yes hello I had done a transabdominal pelvic exam last Friday and today a week later the results say my stripe is 7.2 mm.I am goin on 48 in may and didn't get my menstrual cycle in jan or feb yet but did in dec.my periods have been irregular like every other month or 2months in a row etc.the results say I have a small fibroid in the anterior myometrium measuring 1.7 cm without mass effect on the stripe. My right overy is2 cm and left is 2.4 .the right ovarian follicle measures 1cm and no adnexal masses at this time.could u help me to understand better and even tho I haven't had my period yet in longtime I have been experiencing bad cramps in past week or so on n off