Honestly, and I know you have probably thought this already, but for anyone to walk away from a relationship based only on the size of your penis, is a relationship not worth having in my opinion.
I was 6.5 inches, I had to have surgery on my penis and lost 1.5 inches. No one has walked away because of that one reason (or at least they never said it was for that reason).
I guess I look at it this way, sometimes a guy might like a gal with "a cup" breasts and fall in love and then he might later fall in love with that gal that has "ddd cups". I don't think that breast or penis size alone is the sole reason most make their decision on who to date. At least thats my two cents worth.