Hey! I am 26 years old and I had the same problem. Could not maintain or get full erection .I thought it was the end, but I decided to do something , I found some informations on internet but it didn't help very much, what really helped me I'll write down:
1. Stopped to watch porn . really difficult decision because I watch porn since my childhood. To stop smoking sigarette was more easy haha!
2. I stopped masturbating. I was masturbating also when I had girlfriend, because we were not doing every day or when I wanted she was not near and so on. I thought to masturbate is like having sex so it should not influence on my sexual life. but its not like this, because you have to be aroused only watching girl nothing else have to substitute woman.
3. Most important, I understood that nobody is perfect in anything, also my girl , so she have to accept my problems of erection (temporary as it turned out) as I accept her how she is. I mean I stopped to feel shy or guilty because of not stabile erection (btw I think in most cases this is the real problem)
Of course this helped me but its not "medicine" for everybody, but for sure , solving this things will make you to be much better in sex. In my case in really few time (1-2 weeks) I already saw big difference.
Hope could to help you!
You definitely do not have to be impotent.
The first question is where to start. Repairing this function is not quick and easy, so get ready for another possible 2 years to recovery.
First step, get rid of the porn. There are mental issues with porn I will not go into here. Second step, do not go for a climax more then once a week. It is healthy for the venous valve to get erections whenever you can.
If you see any improvement at all, maintain this. Some say kegel exercises help, even without proof it may help.
If after a month of this if you see no improvement get an appointment with a urologist to evaluate your venous valve. An operation can fix a damaged valve. However, the recovery time to get it functioning well is long.
Viagra will not hurt future activity. If you use this and it provides a good erection for an decent amount of time, it is not your valve. It will be your excitement level, which is the mental part, normally Porn related. If you refrain from porn, edging only and restrict your climax to once weekly with your partner, you will gradually get better. As time goes on be adventurous, you never know what might elevate your excitement. But do not get stuck doing whatever you find over and over.