There is absolutely nothing wrong with masturbation. Guys do it, girls do it. Married people do it, single people do it. Old people do it, little kids do it. Many, many people masturbate.
If ANY of the rumors about masturbation were true, then there would be billions of infertile, horribly ugly, physically weak, blind, hairy-palmed, mentally handicapped people out there.
You're 14. Stop worrying about "getting girls". They don't want you at that age anyway. It's all fake at that age. People date or do it to be "cool" or whatever.
Masturbation, despite the rumors, does not actually have any effect on sports, or mental capacity, or sexual prowess, or attractiveness.
Also on a final note, God isn't punishing you. Then again, I'm not Christian so my words on that matter really don't count. But seriously, he gave you a penis and free time. I don't think he's going to mind you enjoying yourself. Heck, he gave girls a clitoris, which has absolutely NO purpose except to feel reeeeaaaally good.