You're talking about 2 issues here - masturbation and porn. Masturbation on it's own is a normal healthy activity that men and women even children do. If you're in a committed rerlationship, then masturbation is fine so long as it remains supplementary -meaning it's not taking away from sex with your partner.

The same would go for porn. It becomes a problem if you become addicted to viewing it and masturbation becomes your predominent sexual activity. Another problem that comes from watching too much porn is 'desensitization' - this happens when the viewer starts to have trouble getting aroused in a normal sexual situation with a partner because he no longer finds regular sex stimulating - because he has become in the habit of always pushing the thresh holds of excessive stimulation. In other words regular sex seems boring.

If you're not happy with how you feel afterwards, then perhaps it's time you speak with a therapist about this. Do you have a regular sexual partner? I think you should start relying on your imagination to masturbate and doing this is perfectly normal. I don't think it causes cancer - if anything not having regular orgasms could cause prostate problems. Did you know even fetuses in the womb touch themselves. Everything in moderation is key. Good luck.