Ditto to all the suggestions of stepping up on familiar runs. Catch tight eddies, make hard ferries, get your stroke timing and powerful draws dialed in. Then run class V. At 16, there's no need to be in a hurry to run hard stuff, be in a hurry to develop good decision-making.
All that said, take a look at Natural Bridge (IV) on the NF Rogue in Oregon. The local community in Ashland and Medford go up there on a regular basis and it'll add a new river and perspective to your list. It's also a gorgeous summer trip. If you're doing awesome up there, someone might be willing to take you into Takelma Gorge (V-) just downstream. The local paddling listserv is: waterdogs at lyris.dundee.net. Send out a plea for help when you're passing through.