I am on loestrin 24 fe for about a year with sometime no period or just light. also this month pain on right side - could it be ovarian cysts?

Pelvic pain: Given that you are on birth control, the chance of ovarian cysts and pregnancy are certainly decreased. First, the lighter or absent periods is common on the pill. Second, the lower dose pills might be associated with less effective suppression of cyst formation. You need to perform a pregnancy test, and if your pain is significant, you need to contact your doctor for an exam and ultrasound!