From the government guidance on isolation:
"If you do not have symptoms of COVID-19 yourself, you do not need a test. Only arrange a test if you develop COVID-19 symptoms or if you are asked to do so as part of a wider testing scheme. If for any reason you have a negative test result during your 10 day isolation period, you must continue to self-isolate. Even if you don’t have symptoms, you could still pass the infection on to others. Stay at home for the full 10 days to avoid putting others at risk.
If you develop symptoms while you are isolating, arrange to have a COVID-19 PCR test. If your test result is positive, follow the advice for people with COVID-19 to stay at home and start a further full 10 day isolation period. This begins when your symptoms started, regardless of where you are in your original 10 day isolation period. This means that your total isolation period will be longer than 10 days.
If other household members develop symptoms during this period, you do not need to isolate for longer than 10 days."
OP is not doing anything wrong if she it outside of her 10 day window. The guidance is clear that if someone in the household develops symptoms during their period of isolation, the clock does not reset for those already infected.
So stop piling on her!