Well. I'm 29 and have been masturbating (contiously) for about 17 years.
I think you should really try to use your fingers and give the magik wand a rest!
When I got my first vibrator, I totally over-did it. I used it morning, noon and night and after a while, I was unable to bring myself off without it!
That sort of scared me and I threw the wretchet thing away. It took me about 2 weeks to get the magic fingers back!
Since then I have acquired new vibrators, but I never let them get the best of me

It takes me about 7 minutes to orgasm if I start cold, but with the aid of porn it takes about 3-4 minutes.
I have no clue if that is long or short, I just do what feels good and go with it
Also, I come faster if I lie on my stomache than if I'm lying on my back... the position could be a factor as well.

If you are worried about your orgasms taking longer, that could be the reason they are taking more time! Stress (especially sex related) has an effect on every inche of your bodies... the clit is not excluded from that

So, stop masturbating infront of the TV, get nice erotica and use your fingers!