Ask them to show you listings of deals they have closed. That's the only way to know for certain if they told you the truth.
Also, the other thing to do is to calculate how much real estate you have to sell in order to break even into what you have already put in, and what you will continue to put in.
The money you have already put in is sunk. No matter what decision you make now, that is gone. So, the question becomes, if you invest another $100 on X training, or $200 on Y desk rent, how much do I have to list or sell to recover this.
As a rule of thumb, a selling agent can get about 1.5% of the total sale, or $1,500 for a $100,000 sale. If houses in your area typically sell for much more than that, you will do better. If they sell for lower than that, you will have to have greater volume to make up the shortfall.
The realtors I know are doing well in the Washington, DC area because the market still has some movement among lower priced houses and first time buyers. It isn't as lucrative as it was before, but they do ok. They also have a loyal client base and can rely on repeat business and referrals. If you know some people who are in the market for houses and can give you leads, I would say your chances are better.
So, do the math. Figure out if putting more in will give you a chance to make back enough to justify your effort, or bail out before you are too far in.