Well man it happens. I see many guys here who become insecure after their girl calls their penis small.
If your girl never seen real thing before then she knows only how they look in porn where everything is oversized.
Anyway its hard to lie to people ypu love and shes been disrespectful to you with calling you in that nickname.
After all this is how she affects you. Decide if shes the rigjt girl and you want to that kind of person around you.
If you take away her beauty, would you forgive her what she did? Maybe you are under beautiful women spell thats why dont see how bad she treats you. Or are forgiving these unforgivable things. Love without respect is like angel without one wing - it cannot fly.
Doubt kills more dreams than failure ever will