Your meme's on their own are fine, but in my opinion are most likely to be upvoted by people in a similar life situation (being in high school, maybe middle school). Believe it or not, but a large portion of the imgflip community is 30, 40, 50 or even older. A lot of the "crush" memes don't really resonate with us anymore.
For me the fun is commenting on other's memes, and I just try to make my own memes as funny as possible. Hell, I'm in the top 75 alltime, and on the weekly leaderboard and I've got memes this week without 10, and in some cases 5, upvotes. Sometimes it has to do with visibility, time of day and the age of the audience seeing your memes...along with many other variables. Sometimes its impossible to predict what will make the front page.
My one meme the truly hit the front page, was in my opinion the least funny of the three I submitted that day. Jying also commented recently that he didn't his Mrs. Potato Head would do anything but essentially burn his third meme, but it made front page.