How fertile are you after giving birth?

Kennedy • Married to my soulmate since 7.4.2020!💍💞 We have a 4 year old son, who took a year and a half to conceive! We are expecting baby girl March 11th 2021 after 2 1/2 years of ttc with fertility treatments 💖
I have birth 11 weeks ago... and I think I might be pregnant again. Yes I'm on nuvaring but I've had my period since giving birth. My period was expected Monday when I removed my ring. And no period so far. I've had cramping like I did with my first, increased discharge, very nauseous, starting to get a cold like with my first, I'm having headaches, and I'm light headed. I'm craving barbecue like I did when I was pregnant before and the thought of eating what I usually do at my favorite carry out place is not sitting easy with me. I'm going to test if af doesn't show by the time I'm supposed to put my new ring in (this coming Monday). I just want to know what's the likelihood of being pregnant even using birth control within 3 months after giving birth.