Is It Normal To Skip A Period After Childbirth?

Im 6 months postpartum. Breastfed for 2weeks .Had my daughter 8/7/14 had my first period 10/10/14 then another one 11/14/14 and one more after that in December . But i havent had one since. Pregnancy test was negative. No symptoms. Jus missed pperio. Is it normal to skip a period after child birth?