Ttc late by 8 days on period. i am so bloated and uncomfortable. tired. however neg pregnancy test. what else could it be? never been so bloated!

Hormonal Dysregulati: Sounds like lack of rhythm of normal monthly hormone changes. See a doctor. May reflect some type of stress physical, metabolic, or psychological, or even pharmacological.

Menstrual cycles: It is common to skip a period and have irregular cycles on occasion, especially if you are very athletic, gain or lose weight over a short period of time, are using birth control pills, or have an eating disorder. I would track your cycles to see if it happens often and see your doctor if you notice that it becomes more irregular.