Wow

Only just coming to the end of your first year and you've already built a substantial business that also provides enough work for a full time employee??
If I've read that right you've done phenominally well!
My advice would be to consult an accountant as soon as possible. We were advised to become Ltd in 2009, having been Ltd some years earlier and then reverted to Sole Trader. The benefits had changed, making it tax efficient for us to become Ltd again.
As a Ltd company your company employs you, pays you a salary which uses up your tax free allowance so you pay a small amount of PAYE plus your employee and employer National Insurance, then the remaining profits of the company are taxed via Corporation Tax. Overall we are slightly better off doing it this way.