zipzap, I could have written your post!
On my Mum's side, my Mum and aunts mostly had girls, out of my Nana's 17 grandchildren, 5 were boys, the rest of us were girls.
I had 2 sisters and then, after a seven year gap, my Mum had my brother. With hindsight, I can see that my parents were actually delighted to eventually have a son but I was a little disappointed as I loved all things girly.
Now I have four boys and am expecting a fifth ( or at least I presume it's a fifth boy! only 9 weeks but too early to tell.)
I have finally managed to convince myself to love being a Mum of boys and that that is actually fine. When I found out ds4 was a boy at a scan, I was devastated but having been taught the same lesson, over and over again, I have finally learned that my boys are gorgeous and cute and that I don't care if this baby is a boy!
I think in our culture, little girls are more valued than little boys. If you go into any high street shops, there are acres of cute clothes for little girls and very little for boys. Also, I have noticed that there is a pink version of everything but rarely a blue version. Mums of girls want to actively show that they have a girl, Mums' of boys tend to go for non-gender specific colours, so you have a bright pink version and then a lime-green-and-orange version.
Also some Mums of girls say annoying things like "Oh, I don't think I'd know what to do with a boy" as if you were talking about a badly trained monkey, rather than a human child.
But little boys ARE gorgeous and bigger boys are great fun. You just have to learn to see it!