Hi Skittles16, welcome to the forums! It sounds like your little one was very lucky indeed to survive such a serious injury!
It would be interesting to know approximately how old Skittles is. Green cheek conures reach sexual maturity anywhere between one and three years of age, so that may well play into the biting behaviour, as GCCs can become bitey and aggressive during this phase. She may be biting you because she has chosen you as her preferred "mate" (yes, it happens!), and she wants to keep you away from the threat to that relationship that she sees in your dad - this is called "displacement biting". Or, she may even have begun to show a preference for your dad so she is being extra sweet to him but bitey with everyone else!
You should ensure that your GCC does not have access to anything that might even remotely resemble a nesting site, so if she has one of those hidey/cuddle hut arrangements made of synthetic fabric that will most definitely have to go as they can be a huge trigger for aggressive behaviour as well as a choking hazard in many species, not just conures. For my lorikeet Lilly it's dark little spots behind the cushions on the couch that get her going so I have to strip all cushions, throw blankets etc off the couch during the day. You should not pet or scratch anywhere other than the head or neck either as this will trigger aggression too, since they see this as "foreplay" and get very frustrated when those needs cannot be fulfilled.
Just occasionally though, sudden behaviour changes and aggression may result when a bird is ill or in pain, and this may indeed be relevant for you given Skittle's accident. For this reason it's often a very good idea to have them checked out at the vet, particularly if she has not been wellness checked in the last 12 months or so. Understanding that there may be limitations on availability in your part of the world, the following link should help you to find an avian specialist near you if not already acquainted with one...
Good avian vets are also an absolute gold mine of information around behavioural issues as well.
Thank you for joining, and I hope this helps you!