Hi T, You are suffering from over masturbation, try doing an 8 week break from masturbating and any sexual contact with your g/f, now this one time that you will need to be honest and open with your g/f, why you will need her help, as this is 8 weeks of no touchy, touchy, now if you can do this it will be away of rebooting your body, and get your sex life back on track, so if things work after 4 weeks you should be getting you nocturnal erections back along with morning woods, but still now playing and round with it, the best thing you can do for the 8 weeks is just wash it and look at it.
But as you have been doing this for a long time you may need an extra 4 weeks, see how this fits into your life style, but you may find its your only way back to a sex life.
I would just take Lp-argimine and take up running or weight lifting and they'll be back. If not, it could be a sign of something serious, meaning you need a checkup with blood work. Diabetes is one cause of loss of erections. Erections are a barometer of men's health.
An offhand comment I heard from a doctor. When a patient suddenly can't get it up, they assume it's something physical. When function slowly disappears, they assume it's all in their head. The reverse is true.
If you're afraid of not getting it up, that causes stress, and stress results in limpitude. Limpitude means more stress.
I've been 'blessed' I guess with some female friends who over share. Your 'problem' is pretty common.