I'm expecting my third and have a girl and boy already.
I did carry differently with the first two. With my girl I gained weight all around and with my boy it was more of a neat bump just showing at the front. My friend also had a girl and boy and experienced the same thing, in fact, when she was first pregnant she told me she was sure she was having a another girl, then I didn't see her til she was 5 months along and as soon as I saw her I guessed it was a boy from the bump!
My pregnancies were also very different. I was very sick with the first one (girl) and just had slight nausea for a couple of weeks with the second one. I had a lot of headaches in the first trimester second time around though.
Emotionally, I often felt very angry in the second pregnancy. I googled it and lots of people reported the same when they were expecting boys. I read it could be to do with the testosterone circulating.
I'm only 8 weeks along with this pregnancy and it has been different to both previous ones although more similar to the second. I've felt more sick this time than with the second one but not as bad as first time around. Emotionally, I've felt the same as the second one so I'm guessing it's a boy.
Have you looked at the Chinese gender chart? It was right for me both previous times and says boy this time.