When I was pregnant with ds I had terrible morning sickness for 12 weeks, I also felt so tired I couldn't get out of bed for 4 months. I've just found out I'm pregnant and feel well except for a bit more tired than normal and slight indigestion. I wondered if you tend to be more sick with boys and feel worse in general. Also my breasts are really painful at the sides and they weren't at all sore last time.
I didn't have any morning sickness at all and had a girl. My mother didn't have any morning sickness in either of her two pregnancies and had a girl and then a boy. I think it just depends on the person.
I had terrible all-day every-day sickness with all 4 of mine from about 11 weeks until they were born I had 1 DD followed by 3 x DS.
I did carry them differently. With DD I had a very small bump but put on weight all over, so that in trousers I looked like a barrel. With DS1, at 7 months I didn't look pg from behind- it was all out front.
I simply don't believe in these theories. They don't make any scientific sense at all. If you want to know the sex, ask at the scan, that's my advice
BTW I had a boy and felt fantastic throughout. Strong as a horse and not even the most fleeting nausea. We're all different, and every pregnancy is different.
However, there is evidence that boys are more difficult to give birth to - possibly because they are a bit bigger..