Period is 3 weeks late, neg hpt, slight increase in fatigue and lower back pain/stuffness. could these be early signs of pregnancy?

Absolutely: Should eat well and keep hydrated. Avoid medication and retry hpt in a week. If no result, may need to see you doctor for additional tests.

If you have taken a: Pregnancy test that is (-) 3 weeks out, then you are not likely to be pregnant. Missed/late period: low body wt, obesity, weight ^ or v, ^exercise, endurance athletics, breast-feeding, stress, illness, eating disorders (bulimia or anorexia), anovulatory cycle (no egg released), travel, perimenopause, just starting menstruation, hormone irregularities, drug use, meds (i.e., birth control) or >.