Cheri, don't equate BC hormones with having low libido. I'm living proof it just ain't so! Just as many women not on BC have low libido problems. Birth control hormones always gets blamed for weight gain too- though those same women probably would have gained the same weight if they were not on the pill. Everyone seems to be gaining weight these days in America- regardless of whether they are on the pill or not! (note to self- keep riding my bike!)

Again, a cervical cap, a sponge, or a diaphram might work quite well in your situation. They are very non-aggressive and non-invasive methods with no long term ill effects at all. Their only drawback is the inconvenience of putting them in and out- but if you only need do it once a month or so that's hardly a big deal! Sponges are expensive if you use several a week, but that's not your situation at all. I too would stay away from IUDs- I had a bad experience with them long ago as well.
Good luck!