Irregular bleeding after delivery.

Hi dr, I gave birth to a baby 12 weeks ago via c sec. Post that I had lochia for about 4 wks and then spotting for a week ( brown to yellow). At 6 weeks, I had again a reddish brown bleed for 4-5 days ( medium to less flow and changed color from red to maroon to brown) then nothing for a week and only yellowish white discharge, then again at 8 weeks bled for 3-4 days ( started with maroon Nd ended with brown Nd flow was medium to less) , same period like thing at 10 wk and again at 12 wk. I got ultrasound pelvis done and it was all clear at 8+ wks. What could be the reason for such irregular bleeding?. I am mostly breastfeeding baby with once or twice formula daily. Attaching the scan pic as well. I am really upset as it is interfering with my daily life now .