Your baby is probably going to be too young to experience any jealousy like you might think will happen. They will be close in age and they'll have a close bond.
And, I'm sorry to say this, but your body never 100% bounces back anyway. Something is always going to look a little different. Bigger hips. Saggier boobs. Stretch marks, etc. Welcome to motherhood.
As far as the nausea, some women eat small meals. Some don't eat anything. Others eat a certain food (ginger or jello or whatever else) and swear it is the only thing that saved them. Others use seabands. Some crackers. Everyone is different and unique. If it is terrible, talk to your doctor about giving you something for it.
And sleep when the baby sleeps. You'll need your rest.