if you ovulate on cycle day 25 and have a healthy luteal phase then your cycle wouldnt reset until the end of your normal luteal phase length.

If you are ovulating and only have a four day luteal phase then your body wouldn't produce hCG and proesterone quickly enough  to stop the shedding of your lining- making it extrememly difficult to get pregnant without medical help. 

How are you determining what day you ovulate?