Do I really need more than one LLC?

If it's for real estate, you likely need a series LLC at the minimum, and a two-company structure would be substantially better. Separating assets from operations is worth the overhead of the extra LLC at formation time and for year-to-year maintenance. If you own your real estate outright, it may even make sense to set up a financing entity that will put a lien/mortgage/deed of trust on the property(ies) to make them even more asset protected.