Will your source of self employment income continue once you move back to the US? If so, you will need to document how you can continue earning this income when you move back to the US.
I went through a similar process a few months ago. I was the beneficiary, and my job continued when I moved to the US. My wife wasn't working. I had an offer letter of continued employment, bank statements, pay stubs etc.
However, before the interview I decided to get a joint sponsor. At the interview after looking at my job documents, he asked if I had a joint sponsor. Provided those documents and he seemed much happier. Of course there was nothing wrong with my documents, as I had proved that my income would continue from the same legal source when moving to the US, but he didn't seem sure about accepting it, I didn't want to push and just wanted the process to be over.
They tend to be risk averse( for good measure), so you might want to consider a joint sponsor (if possible).
