What is your girth, exactly?
I'm not packing, per se, but am a bit on the girthy side - 5.75" NBPEL / 5.75" EG - and administering a blowjob is somewhat of a struggle for my wife. The fact that her mouth is on the small side doesn't help. Often, my wife's sucking on me is limited to getting me erect in a jiffy. When fully erect, teeth, gagging, and eventually a sore jaw are gonna be problems.
The position that works best for us is her laying on her back with her head hanging off the bed. The angle at which my penis enters her mouth mitigates the soreness and gagging issues. Regarding the latter, however, you should assure your wife that it's O.K. for her to gag a bit; she might be self-conscious about it more than she intrinsically minds it. I've also found that taking control of the blowjob sometimes - this doesn't necessarily mean "throatfucking" your woman, mind you - can be helpful in illustrating that a degree of teeth-to-penis contact is acceptable to you. This way next time she tries to give you "full service" she won't may not be as timid about mildly scraping your pigskin. Basically, be open with her, try different things, make a challenge out of it. But the fact is, it's probably never going to be all that it could be. Sometimes I wish I had a bit less girth; oral would certainly be more fun, especially since my wife is, in spirit, game for aggressive mouthfucking. It's enough to almost make me feel sympathy for the guys with 6"+ circumference. Almost. :smile: