According to current CDC recommendations, you should self-isolate until you've met both of the following criteria:
While at home, self-isolate within a separate room of your home if possible to limit interaction with other family members. If you can’t stay 100% isolated in a separate room, keep 6 feet away from others and wear a cloth mask, wash your/family members' hands often and frequently disinfect commonly touched surfaces and shared areas.
You don't need to be retested after your period of self-isolation. But every case is unique, so follow your healthcare provider's recommendations for testing.
If you have a weakened immune system or have had a severe case of COVID-19, the CDC's criteria don’t apply to you. You may need to stay home for up to 20 days after your symptoms first appeared. Talk with your healthcare provider about your situation.