Aw Emily - I can *totally* relate. I didn't know Diva was going to be a girl, just assumed it would be another male (and I would have a good excuse to move out of the house - too much testosterone - LOL!). But thank you was 6 when I was preggo and had really started hitting seriously major gfgness. We had just moved to IL and I remember going to look at an apartment on the third floor of a building, with a balcony. I told husband that we could not possibly live there because I was certain thank you would throw the baby over the balcony. I think it's totally normal to have concerns and I think it's probably good - you'll be that much more ahead of the game when she (and what will her name be???) arrives.
I have to admit I had a moment of "Oh crud" when the doctor announced the arrival of my girl - I knew nothing about boys when I started motherhood but felt like I had a handle on them by then... and now I had to figure out a girl??? But I gotta tell you, having a girl after 3 boys is a total blast. In our home at least, she's so completely different from the boys - very girly, drama queen to the max, and just different. All my kids are very different from each other but with- boys you just kind of get into a boy-groove thing. Don't worry about the clothes - Diva wore a *lot* of boy clothes for the first couple of years. She fortunately was born with a head full of hair so I got to do ribbons and such - no one ever mistook her for a boy. And friends and family (especially family) went wild with girly gifts. I do have to say, shopping for a baby girl is a whole lot of fun - they have so many more clothes for them. I still remember this ridiculously poofy dress I got her when she was about 3 months, frills, lace, big red rose, just ridiculous, but oh so fun to dress her up in.
She was about 2 months old and I went to the library with the whole crew. Some lady was ooohing and ahhing over Diva, and I said something about my worries with her having 3 older brothers to deal with. The lady looked at me and said "oh but you *know* she's going to know exactly how to deal with- men by the time she grows up". It was a different perspective and I think a good one. The boys are very protective of her (except Wee who I think would still like to sell her in a garage sale, LOL) and Diva absolutely idolizes thank you in spite of all the junk he's put her through over the years.
It's going to be ok. Your girl will bring another dimension to your family. I really do think it's normal to be worried but... it *is* going to be ok.