Hi, From your history i came to know that you have two different kind of problems in a same area.
1. Regarding your difficulties in getting or sustaining erection: As you are young the possibilities of
erectile dysfunction due to blood supply or nervous problem in your penis is very unlikely. Probably you should have psychogenic erectile dysfunction which may be caused by fear, anxiety about your performance, insecure feeling during act, guilty feeling or pain during erection due to lack of retraction of your fore skin. Any one or more of the reasons may be the cause. I recommend you to check the erection during early morning or sleep time ( can be checked at the time of passing urine at late night). if you have erection during these times at least once in a week,its totally psychogenic. So you need not worry about this,because it is transient only. Don't feel panic about your problem, because it may worsen your situation. focus on the pleasure only during foreplay, not on the fear of erection.
2. The second problem is difficulty in pushing back the fore skin. It's a common condition seen in many adolescents and young adults, known as
PHIMOSIS. Please
consult a general surgeon or
urologist for that. He may recommend you a minor surgical procedure called as
circumcision, which is a simple surgery that makes your problem cure permanently.
If your erection problem persists after surgery and trying without anxiety ,better to
consult a psychiatrist or
sexologist who will recommend you to do some blood investigations and give you medications to overcome the difficulties. I assure you that this will not be a big threat for your sexual life , can be curable.