Honestly, the only way I'd be able to help you would be to look at it. Melt it, check its crack back, watch the crack back pattern to see if it is under converted (it's amazing how beautifully symmetrical the pattern from under converted pseudoephedrine is) and finally, shoot a bit. I am not there, so the best I can do is theorize.
Have you asked any of your experienced friends for help?
My final verdict is, the issue is not with your shot. If you're shooting .6 and .7 of this stuff, and you're not absolutely gonzo, and it isn't doubling back in volume, your dealer is selling you very cut stuff, or some sort of research chemical.
I hope someone else can come along and hopefully be able to help you where I couldn't! And feel free to post your video if they say you can