Ebf still no period

Before my 13 month old was born me and hubs were trying for 7 years. I suffered secondary infertility...Very probably due to the depo provera pill injection. It was such a surprise when we fell pregnant. I had started working as a gym and dance fit instructor and we think the improved fitness level may have kick started ovulation (I didn't ever ovulate in those 7 yrs) ..I'm still ebf-ing and my little one barely eats yet...he's not interested. But he also doesn't feed much from me. Only for a few mins , a few times a day and maybe a 10/15 min feed during the night. Still my periods haven't returned. I didn't experience this with his brothers and can't help worry I'm still infertile.