According to your description, it seems that you are probably experiencing a kind of sexual disorder called... "lack of orgasm". However, it's not that you experience a real lack of orgasm because you can achieve orgasm via masturbation .... it's that penetration does not bring on an orgasm. The most common reasons for lack of orgasm are inadequate sexual stimulation and psycho-emotional causes. It is hard to say what is the real cause may be in your case but it seems that watching porn-movies and masturbating at the age of 5 may have psycho-emotional consequences for an adult sexual life. You probably have gotten used to achieving orgasms by self-satisfaction. Why don’t you try masturbating in front of your partner? Then he could try satisfying you by “fingering” or oral sex. Finally you may achieve orgasm by penetration. You will need some time to overcome the problem.
You can ask for an expert opinion from a psychiatrist who specializes in sexual disorders, called a "sexologist".