Skin covers the head of my penis when in erection! is there a problem?

Hi im 14 Years old nearly 15 and during erection the skin still covers the head of my penis, but when i pull the skin down during erection it starts to hurt :S
i can pull the skin down when flacid, but even when i pull it down b4 i masterbate the peice of skin that attaches the skin to the head of the penis starts to hurt ? :S

need help because i have a gf we have been thinking about sex latly and was just wonderin would havin the skin over the head of my penis affect my performance ? or would there be problems with a condom ect, is thiss normal? or is there something wrong? any tips?
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thanks