Welcome to HealingWell!!
I actually was the opposite... My IBS began when I got on the pill (Necon too!). It took me 7 years before I connected it. I can't really help you with this, as I am your exact opposite, but I can say hormones sure seem to play a big part in IBS. Lots of people are prescribed anti-depressants which help with seratonine levels, which in turn helps the gut (most of our seratonine is found in the intestines).
Have you thought about
getting back on the pill?
Have you had your hormone levels checked? Maybe see if you can get in with an Endocrinologist.
I hope you can get this figured out...