Breastfeeding, after c sec in sept. still no period. endometrial thickness 5,9mm. was told no follicle yet. is it normal?

Probably normal: If you are exclusively breastfeeding and doing it successfully around the clock about every 2 to 3 hours, your pituitary gland is producing a hormone called prolactin in sufficient amounts to prevent ovarian follicle maturation and block your ovulation...and therefore block your menstrual periods. This is usually quite normal and not a cause for alarm.