I suffer from this. Here is some real advice. The key is to force the boner and vent the anxiety. It's taken some experimenting, but I found the solution, at least for myself.
1) Order the blue pills from the Indian pharmacy. I use alldaychemist.com, they have them listed as Manly. They are very cheap and I cut them in half.
2) Stop eating several hours before your appointment. Like, seriously only eat 1 small meal long before your date. Don't even drink more than what it takes to get that meal down. Lesser the better. Take the half blue pill about 2 hours before go time. Longer the better, you will be good to go most of the day after dosing. This "forces" the boner.
3) Sooth the nerves with moderate alcohol usage. You will probably know the right amount already. Just enough to make you feel "loose" and talkative, but not so much to be "drunk". Think 4 beer buzz. Takes a lot of the edge right off. This kills the anxiety.
Last bit of advice. You will know you're good when you take the pre-appointment shower and you are thinking about the provider and/or looking at her pics and straight getting super jacked/hard with minimal hand attention to self. If that's the case you will have it made, no probs. =) I don't have low sensation so I'm able to complete w/o issue, but the final release may be a bit diminished due to all the blood pressure up there I guess. At least you will get to feel like a stud and experience the woman though, as opposed to getting the damned "look". And oh man what a relief that will be.