For my taste, the 35 is too large for an every day bag. I would use that more for traveling or an overnight bag. I don't think I could pull it off at 5'7", but it really depends on your personality and style, too, and it is possible that you could pull it off, but I would need to see it to give you an answer.
I had the 30 and just got the 35. I absolutley love the 35. Its big, but not too big..BTW I'm 5-8 though. It really makes a statement. I'm so glad I decided to keep it. I haven't stop using it since I got it.
You have a little one so you may need the room. Personally I love my 25 and find it big enough. If I were to go bigger I would get the 30. (I am 5'3 on a good day..haha). I have seen pics of people with the 35 though and some can pull it off. To me it would too big. I have no idea what I would carry in it!