At my wedding we had mixed seating but separate dancing — and a very high mechitzah so the women didn’t have to worry about male gawkers.
I don’t think anyone says that separate seating weddings are asur, but you might want to consider the feelings of your family, especially whether they will be upset and might have a bad time if they can’t sit together, especially since they know that mixed seating is common in Orthodox weddings. Kvod Av v’Em is an important mitzvah. What many do is to have tables with separate seating for those who prefer it, and tables with mixed seating for those who Do Not Understand our ways. This is worth a consultation with an understanding Rav. Another consideration that I’ve seen attributed to Rav Henkin is that mixed seating for singles increases the possibilities for shidduchim.
I wish you all the best on your wedding!