Week Calendar is your solution!
There is an amazing calendar app called Week Calendar by Utilitap. Though the name is WEEK Calendar, that is only one of the views. I am very fond of the Mini-Month, and Agenda views, as well as the Week View. You can repeat events every 3 months on the second Tuesday, or any other complicated repeat you can think of. The thing that is incredibly amazing about this App is that when you email them a question, they respond within 24 hours, and I've been answered even within a half hour! The native iOS calendar is pretty stiff and unyielding; Week Calendar is the perfect solution! Oh, and Week Calendar "talks" to the native calendar, so you won't have to work very hard at all on your changeover to it -- email the Utilitap staff for help. When you look at the glowing reviews in the AppStore, you'll see my latest review, too. Enjoy!