I had period twice march month beginning and end but april didn't get period at all took pregnancy test and was negative have uti for 3 weeks back pain, frequent urination and slight cramps, passing gas,hungry more what do i do i'm a week late?

Irregular timing: of ovulation, is most likely reason, delayed or absent ovulation will cause you to be late. Possibly polycystic ovarian syndrome, could be a cause. See your doctor for testing and treatment, to correct ovulation issues.

Need imaging & labs : Recommend Gynecologic evaluation including abdominal / pelvic imaging along with lab work + hormone levels.FSH,LH,TSH and Prolactin.