Take it easy, you’ll get your vr legs eventually. The key for me was to learn to detect when my body was starting to feel bad, stop immediately and go take a break. If you stop the symptoms early you can take regular short breaks instead of being drowsy all night.
Also, find some easier games for your stomach. Typically, stuff in a vehicle/plane/spaceship is easier for the brain because it understands something is moving but not you.
Static games work too. Beat saber is the classic but I’d like to recommend SynthRider.
Also, play around with the settings when you’re fresh and see what works. The black blinders on the side help most people but it make nausea worse for me.