There are several reasons of delayed period/irregular spotting like hormonal imbalance, stress/ anxiety,ovarian cyst
/PCOD,thyroid problem,wt gain/extreme loss,irregular eating habits etc.
Need to investigate properly to rule out underlying pathology initially by USG lower abdomen, Thyroid profile, LH/FSH,blood estrogen & Progesterone
etc with Husband semen analysis
.So consult with your doctor and take suggestive measures.
Do intercourse around ovulation time by using Ovulation Prediction
Kit.Ovulation occurs approx 14 days before due date and be prepare for those 3-5 days.
Avoid stress,take healthy diet with Vit-E & Folic acid supplements,control body wt and proper sleep.