These symptoms are a bit vague. If you had an unprotected intercourse
then might be that you are pregnant. But swollen abdomen and movement dont happen so early in pregnancy. So dont worry and get your blood tested for beta hcG or urine test for pregnancy which will be positive by now if you are pregnant. Incase its negative, then visit a gynecologist to rule out other causes of ammenorhea(absent periods). Also get an ultrasound
done, if its normal then you can take progesterone
tab for withdrwal bleeding.
As you say you have irregular periods
and now missed them , it can be that you are approaching menopause
considering your age.
To confirm this you get a serum FSH done. IF is high it suggests menoapuse , also endometrial thickness of less than 4mm on ultrasound would support the diagnosis.
You would be better guided when you visit a gynecologist personally as she can get a proper step wise tests to know the cause of irregular periods in your case.