I don't have any more missions to complete but it says to complete 22 more?

More should pop up at some point.

Missions periodically pop up over the course of days/weeks.

If I'm not mistaken, there's already been 40 or so worlds missions that have been attainable, including the week based missions (most of which are no longer available), the "Play Like The Pros" weekly (also mostly not available anymore), "Watch & Earn" (6 in total, each seems to appear 4 days after the previous is completed), the Halloween missions, the Pick 'Ems missions, and even a couple hidden missions (watch 30/50 worlds games).

If you're currently sitting on only 13, then I'd say you probably wont be able to reach 35 with what's left.

You missed out on a ton already which had in some cases a 3 day duration so when those expired you're screwed. The counters are meant to have you do all of the quests from the start as they're released up to 50 for the mythic icon :/