I am just getting into this whole DIY composite stuff. As I understand vacuum bagging the more you pull the better. It sounds to me that 12" is not nearly enough, if you have bubbles. The 22" sounds closer to what you want. When you get done with vacuum bagging, the part will not a have a glossy nice surface it will have a very dull surface that looks like it has little or no epoxy in it. The the next step then is to finish the part with a clear coat or something of this nature.
If your max vacuum is 22" and you still get spots where there is glossy surface on your part (overly rich resin area) try using a epoxy with a longer pot life eg. 1-2hr.
Like I said I'm new at this also, but I hope this helps, let me know if you have any questions.
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