hello madam ,
Welcome to Health Care Magic ,
relationship between stress
and periods is still unknown to an extent as in your case . However, stress certainly plays a role in suppressing the functioning of the hypothalamus
( Part of brain), which controls the pituitary gland
— the body's master gland present in brain— which, in turn, controls the thyroid
and adrenal glands
and the ovaries; they all work together to manage hormones.
so stress can be a factor for missed periods as in your case , secondly you have mentioned use of condoms does not predict 100% protection from pregnancy
it has its own failure rate too .
which birth control method you are using you have not mentioned it ? having sex singly time is enough for Conception .
Kindly do UPT ( urine Pregnancy Test ) at your home only as these kits are availible at any Medicine Store nearby . If it comes positive you can plan accordingly , as far as in your case normally during periods or just day or two before usually girls show these symptoms of pain in abdomen , headache's etc etc . So go ahead do a pregnancy test and USG Scan if necessary if all these dosn't help do consult a GYN/OBG doctor