Hey man great question.
Sexual Confidence is something usually based on experience, with confidence come the confidence to suggest positions, and to ask if she likes the techniques you use down there

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On lasting longer, I read a book called "50 things all guys should know" (or similar title) and in it there was a chapter written by Peter North. (if you don't know Peter North; he's the cumshot king of Porn.)
He said that one method he uses to last longer is to come close to your point of climax and change position. The break in the sex is usually long enough to bring your 'members' excitement down just enough so as to give you more time.
Other methods include squeezing the tip of the shaft, (just underneath the head) when you're about to come. I haven't tried this but apparently it works.
On increasing your size, there's a website that is full of techniques and tactics to increase your member. I think it's $50 to join for a lifetime membership.
www.massivemember.com
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Your man,
LoveJunkie,