Hello fangala,
It sounds like you're tracking Fitness just on your iPhone! This user guide goes over how to track your data: Track daily activity in Fitness on iPhone
We also recommend checking your device for other data being added to your Health app from other apps. Imprecise location, or data from other apps, may be contributing to steps counted: Manage Health data on your iPhone, iPod touch, or Apple Watch
"Add information from other apps
- Open the Health app.
- Tap your profile picture in the upper-right corner
. - Under Privacy, tap Apps. You can see apps that you already own that are compatible with Health. If you don't see an app, it might not be compatible.
- Tap an app and turn on the health categories that you want that app to track."
Regards.