I'd be a bit surprised if anywhere recommended the sponge. I've never used it, but that's because it was quite expensive and spermicidal from memory. Anything spermicide is going to affect your taste, and not in a good way.
If money is no object, and you are ok with less than IUD reliability, you could consider Persona - it tracks your fertility by a combination of testing your pee several times a month (this uses special sticks, hence the costs are ongoing) and the experience of previous cycles. As cycles can change, it's not as reliable as some people want, but...