I have a Herbalaire, and looking at your problem, I can only see one answer - defective herb. If your bag is filling (so you have air passing over it) and your herb is brown (so the active content is definitely being used - even if it were burning this would still be the case) then what is in the bag should do the job. Looking at mine, there is no way air could fill the bag and not pass over the herb, so that just leaves the 'active content' as the suspect.
There is however a totally different feeling vaping than there is smoking and I have mates who swear it's not affecting them when everyone else is dribbling - even though they look hammered - and aren't satisfied until they smoke some.
Incidentally, I only use mine for direct draw, set at about 285C and I find this uses nearly all the good stuff, while keeping it cool and smooth. Anything higher seems to be mostly smoke - good vapour is nigh on invisible.
I have a Volcano I use for bags (Herbalaire was WAY too much hassle), and I run this at the same temp. Again, there probably is something good left in the leavings, but I gave some to a friend to smoke when he was dry, and he barely got a buzz out of smoking a lot of it, so it's definitely not much and I only get top quality stuff.
I've done a fair bit of experimenting with temperatures and found that the same mates who 'swear it's not affecting them' are a lot happier at the higher temperatures where you can 'feel' the vapour and it becomes more like smoking. I admit when I first started, there was always an unsatisfied feeling, as if something was missing (still get it now, from time to time). I gave up cigarettes about 8 years ago, and it was a very similar feeling to having a pint without a smoke (still get that too, but not very often), so it may be this that you're feeling, and may well have something to do with nicotine withdrawal.
Hope this helps.