i think what you need to remember is that even if a donor resembles you, that is no guarantee that your child will look like you. i have a friend who i grew up with. we always heard from people that we could be sisters. but if my friend were to give me her eggs, that doesn't mean i'd have a child who looks like me. perhaps the coloring will be the same or our eye shape, maybe our height. but the point is, you can't take anyone at "face" value. my friend has an entire history of genetics behind her, whether it be her blue-eyed, dark haired grandmother or her blonde, fair mother. it's a crap shoot and a leap of faith.
the donor that helped us produce our son supposedly could be my sister. i never saw a photo, because we prefer completely anonymous donations. i never cared so much what our donor looked like, but more that she would fit with our family, that she was healthy, young and fit. in the end, my DS looks nothing like me and is the spitting image of his father. but i don't think that people look at my son and wonder if i'm his genetic mother. we have similar coloring, the same color hair, the same shaped face.
so, no, you are not selfish at all for wanting a donor who looks like you. the heart wants what the heart wants, i always say. and quite frankly, i think we all deserve to be a little selfish on this board. why can't beggars be choosers, as that awful saying goes? whatever brings you comfort during this journey and (knock wood) throughout a pregnancy and beyond, by all means... go for it! just know that it may just be that: comfort. in the end, i promise you, when you hold your baby for the first time, you will be so in love that you won't care whose lips he has... you'll just want to kiss them!
good luck to you. i know these decisions are difficult. follow your heart.