I'm 11 days late. i am 11 1/2 months postpartum and have my tubes tied. negative test @ 9 days late. hormonal imbalance or other problems?

Late menses: Late menses are very subjective, there are many factors that can contribute to hormone imbalance in a woman who is still less than 1 year post parting,, stress , psychological response to a crying baby releases a lactating. Hormone that and effect menses. Peace of mind would warrant an over the counter pregnancy test after the first 2 weeks, likelihood is low due to tubal ligation