Period changes after giving birth?

Vanessa

I’m 5 months pp, had my daughter via c section… I had very heavy bleeding for around 3-4 weeks after that I was just spotting even when I went for my 7 week pp check up I was still spotting very little and my doctor noticed and he said your basically almost done with that. I got my period the end of June it was June 29th-July 4th very heavy bleeding like if I gave birth again but I was told it was going to happen like that so I was like alright and then I got it again July 26-July 31 not as heavy as the first time, it actually felt like before I had my daughter. Since then I haven’t had my period I am 13 days late and I’ve been feeling nauseous at times, I get little cramps here and there, I get dizzy and I feel like I’m more hungry but I’ve taken like 3 pregnancy tests and they’ve all came back negative. Should I be worried or has anyone experienced something similar to this …