Are you having a wedding cake because you want a cake, and the associated rituals, or are you having a wedding cake because that is How It Is?
Before you stress about cakes, I'd give some thought to the type of wedding you want, how you want the wedding to reflect you as a couple, and what's really important to you at the end of the day. Planning a wedding is hard. It's not all pinterest-inspired romance. Trust me. A lot of women get caught up in it, but the truth is, if you have a big wedding (100+ guests) there will be so much going on that few people will notice you cutting the cake, and even fewer will care if you even eat any.
Make sure you are having a cake because you want one, not because it's what seems normal. We did not have a wedding cake and everyone gave exactly zero fucks. The Wedding Industrial Complex will try to sell you "tradition" like the government pitches whole grains. Your wedding will be fab, paleo or not, because you're committing to the love of your life. Don't sweat the details if you know in your heart they're just that-- details.