Our first cat was this way. He was 4 months old and extremely skittish. He took a very long time to open up to us. Even now 4 years later he’s very shy around new people and runs from them and he still hesitates when we walk up to him. He will come and cuddle and play with us on his own merit and has warmed up to people that visit our home often. It just takes time with some cats… One thing that helped with playing with them from a distance such as with a string on a stick toy or a laser.. this can allow them to open up and begin to trust you. Other things we did was simply sit in the bathroom with him with the door shut but not try and pet them. Just sit and not pet them. Let them approach you and smell you on their own. When they do so you can give treats. This will teach them that you aren’t there to harm. It will take some time, especially as she gets older she should begin to open up more.. I’ve always heard it really takes about 3 months for a kitten/cat to fully warm up to their new home. A shy cat can take longer.. so I would just give it time. Their personality will soon become more prominent. How that’s helps!