Second pregnancy feels totally different — is that normal?

My first pregnancy I had almost zero morning sickness and felt great. This second one I'm 9 weeks and barely functional — nausea 24/7, exhausted by 2pm, food aversions I never had before. Meanwhile I have a 2-year-old to chase around. Is it normal for pregnancies to feel so different from each other? Anyone else experience this dramatic a difference? Feeling quite alarmed but my OB says everything looks fine on the scan.