I agree with Kelly and the other gals. As people age, their needs change. This is true for men as well as women.
Don't worry, you're definitely not alone. Most of my clients are 55+ (I love older men) and the majority of them have the exact same issue.
You should definitely spend some time in search of a provider who is experienced with mature men. Look at her ratings, of course, but also read her reviews. Of course YMMV, but most men will be very explicit when detailing their hobbytime.
I'd also recommend sticking with older, more experienced providers. It goes without saying that the more years she's been in the business, the more men she's come to know.
And when you do find that special lady, explain your situation and your past experiences, but then relax and let her do what she does best. Remember, she's a professional! I'd recommend you begin the evening with dinner out, flirt a bit during that time, smootch like teenagers in the car. Then when you get back to your place, spend a goodly amount of time kissing, stroking her hair, cuddling - long before any clothes come off.
When things move to the bedroom, take things slow. Engage in some mutual massage, complete with massage oil and aromatherapy, candlelight, soft music, etc. Take things slow. Just sit back, relax, and don't worry about the end result. If it feels good, just bask in the glow of her company. Don't concentrate on the end result. Just let things happen naturally.
If things go reasonably well (even if you don't achieve your ultimate goal), then visit with the same lady a few more times. When people learn what each other enjoy, things improve over time. In my experience, the second date is always better than the first.
Oh, and go to your local naughty toy store and ask the clerk for topical cream that will increase your sensitivity. I use Rocket Balm. But it doesn't work for everyone. Better yet, ask your lady friends to bring their best stuff. You are surely not the first gent they've seen whose Mr. Happy is reluctant to give up the goods. 
If you're ever in Asheville NC, look me up.