Is this mundane?
Somtimes i have these fantasies of have sex with a woman, and she say that mines very tiny. I'm average (6" long, 5" girth).
Answers:
These thoughts are in recent times an unconscious representation of insecurities in the order of your size. You shouldnt be worried about it. Like you said you are an average size, and most women will inform you thats all you entail.
Can you still get preqnant even if you wear a condom?
It is probably majority. You could just include it in fantasies due to concerns nearly your size or you could just win turned on by humiliation.