Can sex cause ware and tear to the penis. Like unwanted stretching.

I am 23 years old but only have become sexually active in the last year and a half. And i guess you could say that
In the beginning i didn't know what i liked so i was willing to try different things. I noticed that i wasn't as sensitive when
my girlfriend was performing oral sex on me. So i didn't mind when she was rough with it. And when we have sex its hard
to keep her wet. It seems like all these sexual acts are waring my penis out. I have only noticed a slight difference in
appearance but i worry that if i continue on this path my penis will get kinda stretched and not in a good way. I don't want to have a lot of excess skin.Its not as if I'm having a lot of sex or anything, its like ounce a week max. That is why I am so concerned Ive never
heard of anyone else having this problem. Is it an issue or is it just natural for a penis to change a little over time through sexual
activity?