I don't know how much you know about the distillation of Essential Oils but there are a few things to do that will increase your yield. Picking the starting material at the right time, when the plant's production of oil is at its highest. Not putting your plant material straight into water but allowing the stem to pass through it, will increase the amount distilled. There is some stuff about this on the Internet; Google "Essential Oil yields" and see what you find.
One must conclude, however, that the amount of Essential Oil produced by steam distillation from any plant is quite small. For example:-
100.0 Kg of Lavender produces about 800.0 gm of oil.
100.0 Kg of Clary Sage produces about 50.0 gm of oil
Using a proper separating funnel makes life easier too.