If your cycles are not before 28days or after 35days interval, its perfectly normal.
changes after abortion
do happen and take few months to settle so it can be due to that. But with age also the hypothalmic pituitary ovarian axis(brain-ovary axis) functions ceases till they completely stop functioning like in menopause
IF you are really worried about getting fixed cycles you can use ocps (if you dont wish to conceive also)or progesterone tablets
to regularize your cycles for which you need to consult a gynecologist personally.Some hormonal tests like Serum TSH,LH,FSH and Prolactin
can be done to rule out any pathological cause. But i think its not at all needed in your case as irregular cycles are significant only when they are out of the range of 28-35days cycle length.