What Causes A Delayed Period And Movements In Lower Abdomen While On An Implanon?

Hello. I've just had my son in July. In September I got the implanon placed in my arm. I used back up method. 20-12 days afterwards. Pills and condoms. Like weeks later my boyfriend and I began to stop using condoms but.. I have been experiencing these little funny movements in my lower stomach, I was thinking maybe it was just my uterus still going down. My cycle stayed on two weeks,started Nov. 9. I skipped December now her I am.I. January patiently waiting.