What size to make?

Im struggling to decide what size to make. I usually make a size 8 with a 3/4'' FBA with Liesl +co patterns. My high bust is 36" and full bust 38.5" and I wear an E cup. The finished measurement for an 8 is given as 42" so there is obviously a lot of positive ease. I dont what the dress to be too loose fitting so Im wandering whether to make a 4 or 6 (finished measurements 40" and 41" respectively) with a FBA or make an 8 and skip the FBA. Any input gratefully received. Thanks