The monk/Quaker parakeets I've met have been super smart and make super strong social connections. If she's only 9 months old and has already been through 3 or 4 homes, she might take a while to trust you since she's been through some major emotional trauma. Maybe try just letting her be and just sit nearby talking to her or reading something out loud. Two weeks is pretty early for a scared rehome/rehome/rehome bird to settle in.
Do you ever eat meals with your birds? This has worked for me with foster birds and even my independent guy gets suckered in to family dinner! I make a salad with all bird safe food, then make little salad plates with pellets and seed added, and put one or two near the birds that don't fly over. Then one or two on the table by me. Then eat!

Every single time my visiting cockatiels come try something new, and my Quaker tries to steal my whole salad

My solo guy even comes closer and checks out everything on his plate.
/QUOTE]
I agree that it's going to take more time. I've had Oscar for over a year and he just stepped up for the first time! Of course, he's 22. Like you,
@Phocyn , I was Oscar's 4th or 5th owner in as many months!
I have found with every bird I've had, the eating with them is an excellent way to bond. I call it the eating game. You have to glance up at them while you're eating but look back down at your food as soon as they catch your eye. It's a game of everybody and everybirdy pretending they're not watching each other while knowing they all are! Then there's the food races! Pretty self explanatory! Fun times!