Hello and welcome to the forums!
There IS a lot of work involved in setting up and running a VA business - but it's well worth the investment. Those non-billable hours do come as a bit of a shock to some though. One suggestion to try to get out from under the overwhelm would be to sit down and list out the tasks you know you need to do to run your business and then group them together according to the type of task (marketing, social networking/media, local networking, learning new skills, bookkeeping, etc. etc.)
Then, create a schedule for yourself, where you're working on certain aspects of your business for X hours on a specific day each week. Then stick to it.
As you come across new ideas for marketing your business (for example) - add it to your list of marketing tasks and work on it on the scheduled day(s).
I know it can feel crazy when you have a list a mile long and it grows by the day as you get new ideas and come across new information, but compartmentalizing those tasks into chunks and then scheduling them can really help you feel more focused and less scattered.
As to general advice on business development and growth: the very best advice I can give is to jump into the forums and read, take notes, ask and answer questions, and get involved. You'll learn so much just by interacting with the virtual assistant community-at-large. Fellow VAs are an awesome resource of information and support!
P.S. Please set up your signature with your name and business name so we know who we're chatting with!