Can you not have your menstrual cycle for 5mos when you're not even pregnant?

It is possible.: Reasons for missed/late periods: low body weight, obesity, marked weight ^ or v, over-exercise, endurance athletics, breast-feeding, ^ stress, illness, eating disorders (bulimia or anorexia), anovulatory cycle (no egg released), travel, hormone irregularities, drug use, meds (i.e., birth control) or medical problems (i.e. PCOS). #1 reason is pregnancy.

Amenorrhea: Sounds like you have amenorrhea. At age 40 it could be a variety of non pregnancy related reasons like use of birth control, hypothyroidism and the most common annovulation. As women get into their forties, they often times have episodes of annovulation and will have irregular menses or skipped cycles. If it lasts more than 3 months you may hemorrhage at some point. Menopause is also possible.