Hello there Collete, how are you doing now? If you didn't treat your problem yet and you still have problems with erection I will try to give you some advices that might help you.
First and I guess most important thing: do you do drugs? smoke or drink? I assume that you might be doing this if you have problem with erection so young. These kinds of things are really exhausting a human body as it needs forces to recover everything: the lungs, brain, liver and any other organ that is affected because of them. So I guess is clear that when it comes to perform a sexual act you simply do not have that power needed. I understand that is really hard suddenly quitting everything, so I recommend you to take it slow.
There is also something that is affecting your powers for getting a hard erection. You said that you masturbate a lot, well that means that you have a low level of testosterone. Testosterone is playing the biggest role in an erection and by masturbating so much your body can't produce the amount necessary for a fully erection. You have to stop it immediately if you want to get fixed. I assume that you will see a change within days if you follow my recommendations.
So my last advice for you is to visit a doctor if nothing from above will work. I'm sure he will check you out and he will be able to help you. Good luck and be healthy!