Weird latch?

My daughter is almost 3 months old. I’ve been exclusively breastfeeding on demand since birth, and we’ve never head any issues. No pain, no bleeding/bruising, and she puts on weight like a champ. However the majority of breastfeeding things I’ve read says that the lips should be flanged out, not tucked in (which hers seem to be a lot of the time?). I never really bothered to change anything because she’s been doing good, but is this something I should be changing? This is my first baby so I’m just going day by day with this stuff