Since it's in the same type of work, and if you can prove a total of a 2-year employment history (self-employment included), and if you've been a W-2'd employee for 6 months, then you should be looking fine to use it to qualify (whether the income will qualify you or not is another discussion).
You do not have to have a W-2 to prove you are employed. You need to be able to provide paystubs, as well as we contact your current employer to confirm your start date, wages, etc. and also to make sure you are an actual employee (and not like a "contract employee" or something along those lines - as that would still make you still self-employed). Documentation that you have ended your self-employment would very likely be needed, otherwise your new employment position could be looked at as a 2nd job which needs a 2-year history at the same employer to qualify.