My problem, when dealing with this issue, was that I couldn't stay hard during sex. If you can, real sex will not do damage. The damage is from the method of jerking yourself off. A vagina does not grip as tightly. It will actually help your penis back to normal if you get used to having sex, while not masturbating. If you keep masturbating this way, and have sex, then it won't help much. But, bottom line, I've dealt with this for about 10 years now (I'm 28). I've even taken Viagra. My d**k still works somehow. I'm sure you won't do permanent damage. One warning I do have tho: Don't let any girl jerk you off wrong! One time, my d**k was so numb and I didn't realize how hard this girl was jerking me off (she was inexperienced). Had the worst pain for like a week after that and could not get hard normally for a couple more weeks. Closest I've come to someone actually breaking my d**k.