A few things to echo others:
1.) Don't worry about teaching. Follow her lead. If she's interested, then"teach". But at this age the learning is very self directed. Only now that my DD is in K are we doing anything that really seems like teaching, because I'm trying to supplement her education primarily to keep her happy and challenged.
2.) There may be times of plateau. My DD knew all letters by 18 months but it's not like she started reading immediately after. Dont worry that she's sliding back to normal or anything. These things go in fits and starts but most likely she'll always be advanced. She learns more quickly than other children, so she will pick things up in a fraction of the time.
3. Stick with reggio. I can't emphasize that enough (unless you eventually choose a grade skip). DD is in a reggio program and although we do some after schooling as well to keep her engaged, she's not being asked to do things that bore her at school. We're also very lucky that our school understands her abilities and is willing to hear us out for future grades, but that varies by school and the level of giftedness in the child. DD hasn't been tested but she presents as a g/mg kid. Hg+ kids have more challenges in school, even in a play based one. So your mileage may vary.
4.) I combat the flashcards accusations on two ways. First, I make it clear in social media that I'm a fan of play based learning and i don't believe children need to be reading at 5. So others' knowing that insulates me a lot. Second, in response to others, I just say something like, "if this has anything to do with my teaching her, I'd patent it abnd become a millionaire! This is all her and she continually surprises us. We just follow her interests and support her whether that's math or Barbies"
