You are in a crowded, but also very narrow, space. WyzAnt essentially owns this market in the US, although there are a couple of minor players. You don't say where you are geographically. In Canada, for example, there is a real void in this area.

Are you putting all your efforts in guerilla marketing, as your comments suggest? That can only take you so far.

You are generating at least some interest. However, most are abandoning your site upon landing. Before you address your marketing, you need to discover why there is no "stickiness." I'm guessing the product is either lacking or not wanted by the audience you are targeting... or is not presented well.

I would be glad to give you my 2 cents' worth if you wish; I have experience in the tutoring and higher education space.