May I first say that it will all get MUCH more clear once you have your bunchkins in your arms. I found that was true for just about every purchase. I used to leave Babies R Us in tears, even though there was almost nothing there that was useful to us (carseat was pretty much it), b/c I just iddn't know what I would need for my un-yet-met kiddo. And then he was here and I could figure it out.
So...have you looked at peppermint.com? They have a variety of carriers.
When DS was itty, I used a Hotsling. It's hard to measure for it when you're pregnant, but I think you could do it now and be fairly accurate. Other "pouch" slings I liked were from mammasmilk.com. She has an adjustable pouch, and also one with an interesting shoulder pocket for dipes (either cloth or disposable).
I also really enjoyed the Moby wrap, and I enjoyed finding things to wrap in the same way (fun from mamatoto.org).
Later I found the mei tai that's in my avatar (we're at
disneyland in the picture), but if I were suggesting another mei tai I would be sure to mention padded shoulder straps, b/c when DS started getting bigger those unpadded straps gave my "hickeys" on my shoulders and front of armpits (not pretty!).
And my last carrier was an Ergo, which I woudl HIGHLY recommend to anyone. They have an infant insert so you can wear it from the beginning. It's a bit more "mainstream" in appearance than the others I like, but it has a nice wide "seat" unlike the Bjorns (which is what makes the Bjorns not all that terrific for pelvic development in the baby), it can be adjusted in a million ways, and if I can still consider wearing my 3 year old, 38 inch tall, 33 pound kid in it...it's a GOOD carrier.
Have I confused you more? Probably.
You don't have to pick The One Forever right now. You can return or resell, or just start a collection like mine (I also have a Korean carrier, a podegi, that my MIL gave me, but I just don't have the podegi-love, at least not for the traditional, made in Korea, podegis).
I do want to mention to you...I personally was never able to nurse in the sling.

Well, OK, I did twice, but the first time I had to be topless, and the second time he was over 1, in a facing-me front-carry on a long walk in the Moby, and anyone in a Hummer or tall truck could have gotten a NICE flash of milk-carrier, LOL. I finally gave up trying, b/c it just didn't work for me. It was the only nursing thing I wasn't able to do!