Periods after having a baby.

So basically I had my son prematurely at 33 weeks as I was really ill with sepsis, had to have an emergency c section so on the 23rd of April my son came along since I've 2 periods, the first lasted a week and the second lasted for ages my last one was on the 23rd of june so I started taking my pill, and I had my 7 day break and had no period so as it tells you to on the information leaflet I carried on taking the pill after the 7 day break and still didn't get my period so I've took the pill now for another month and I'm on my second break I finished my pill packet on Thursday and still no period? Is this normal? I've done a pregnancy test and its negative, and I've always took my pill and we've most of the time used condoms too and he hasn't come inside me etc, (I know you can get pregnant of pre cum) is it Normal to still be waiting for your period? Thanks