I didn't know they could do this....

Yeah. They upped the requirement to 15,000 points. My cousin found that out when he hit the 15K number. And he was gone a lot longer than you.

Just do your 2 a day, comment, especially on popular memes, and you'll get up there in no time.

This is what I've experienced:

Submitting successively memes will help you to maintain 3 submissions. When you have a break of one day, you'll have just two submission the next time you'll come to imgflip.

So you make one (or two) submission(s) and the next day you'r gonna have a third submission again.

But I can only speak for myself!