Empherio, I think you are experiencing a three fold problem. One is the draw technique, which has been explained above and just takes practice. And, as I've said before, this kind of practice is fun!
While using med grade herb is optimum for this style vape, you can still get good effects with mids, it just takes more. But the biggest "problem" you are facing, IMO, is that you are used to higher temp effects of smoking which the LB and your VG will get closer to. My advice would be to "surrender" yourself to vaping for at least a week straight, using only your Zap. Let yourself adjust to the difference in high and the difference in vaping temp of the Zap. Also fool around with maybe adding a little kief to the tip of your stem pack which will increase the "clouds" and duration of a stem full.
And one note on only getting one "good" hit from your stem full. Often, it feels and tastes like there is no vapor, but if the hit is exhaled into the proper light, you will be amazed to see that you actually
did get a good hit. I have had this same thing happen with the LB, especially prior to the PA. So I guess my final advice on this is practice, practice, practice!