That sounds perfectly normal to me I had nausea on and off some days worse than others and other days hardly none (although i pretty much had it 24/7 most days!!!)
Some women get no nausea at all and all is still fine. If concerned though, best to see the GP for a check up but it's pretty normal to feel different on and off.
I'm tired some days more than others too.
Each pregnancy is usually different also and if you've had a miscarriage it's normal for you to be so concerned.

Good luck to you and your wife