Hi So I Had A Baby 3 Months Ago In

Hi so I had a baby 3 months ago in October. I started birth control beginning of December but I only took it for 2 weeks and got my first period after having a baby a couple days after I started taking birth control. I ended up having a period for 2 weeks so I stopped taking the birth control cause it made me moody and made me start gaining weight. After that I had got my period 32 days later on January 3rd but had a shorter period that only last 4 days when my periods have always lasted 7. So now I'm in the middle of my cycle and I have whitefish/yellowish tissue coming out and am kinda freaking out what's going on?