Side effects from stopping the pill can last awhile. In some cases, it can take a year or more before your body gets back to normal. I stopped the pill in june after being on it for 7 years, and I can tell you, my periods still are not normal. I am ovulating and they are regular every 26-28 days but extremely light flow, nothing like I was pre-pill. But if you're not even having a period, you are probably not ovulating. But first, take a pregnancy test just to be sure (though i'm pretty certain you're probably not).
The pill depletes your body of a lot of essential vitamins and minerals. You should try to take some supplements to help such as a b vitamin complex, calcium & magnesium, copper, zinc, and omega 3 and omega 6 fatty acids. You might also try a supplement called vitex (chaste tree berry). Some women who don't ovulate have tried it and had success. It works best over several months.
I too have noticed nausea and still have it, 7 months off the pill. I notice it is worse in my pre-ovulatory phase, from the day my period starts until the day I ovulate (really bad when I ovulate). I've lost about 7 lb. But the pill gave me horrid water retention and bloating.