Breast-feeding and birth control?!

Tania • January 31st, 9:49am weighing 8lbs 11oz 😍
So, I went to my pp check up today and my doctor said if I'm exclusively breastfeeding that I don't have to worry about birth control...is that true?! 
He was saying that if I'm Breast feeding that my body thinks/reacts as if I'm still pregnant (no periods/no ovulating)...so that I don't need birth control but it is still an option. 
Just want to know what you ladies think...