NuvaRing NuvaRing NuvaRing!
Sorry, I just love this relatively new method of birth control. I've been using it for about two years after several years on the pill. It's a once-monthly vaginal ring that you insert, leave in for 3 weeks, and take out for one week before putting a new one in. Lose dose of hormones and I've never had any side effects whatsoever from it. They have a website, nuvaring.com, where you can learn more about it.
A lot of women do experience more gut problems with ovulation. I've never really been constipated so I can't give you much advice there but maybe start increasing your fluid and fiber intake around the days you ovulate; might get things moving faster.