I did that when you click on a post. You get an ad under the post title. Pls check that one out and lemme know.
If you are getting very few clicks (less than 15), it's not bad. If you are getting more clicks (especially over 100), you need to do a lot of optimizing. In fact, if you are getting a lot of clicks, I would think about replacing Adsense because your readers are obviously very motivated and maybe, willing to spend money.
To be honest what you are earning is not THAT bad!!! Yes it would be nice if it was higher but my biggest earning site hase a CPM similar to yours.