Thanks for your query.Based on the facts that you have posted it appears that you have penis of 3 inch length in flaccid state and 5 inches after erection. It is the hardness of the penis after erection that is more important in sexual satisfaction and not the length while in flaccid state,
The length pf your penis is is within normal physiological range and nothing to worry about it.
You had been indulged in masturbation
since last 10 years and now think your problem to be due to masturbation.
First of all there is myth in a mind of common man that excessive masturbation is the reason of all sexual problems But I would like to state that it has been discussed in scientific forums all over the world and proved scienificaly that masturbation does not have any negative effect on any organ or system in the body.All the problems that you are facing now are mind related and due to anxiety
. Following measures will help to boost up your level of confidence and allay anxiety and there by improve your sexual performance in future.,
1) Practice moderate exercise for 45 minutes followed by meditation
for 1/2 hour.
2) Take high protein diet rich in vitamins
A,C,E,D.fruits and vegetables .
3) Avoid alcohol and smoking
4)Take some anti oxidants like Almonds 5-6 everyday.