Hi, welcome back and congrats on your new addition. She is still very young so you shouldn't expect much from her as far as talking goes. If you play a variety of things for her, she probably won't pick things up that way. I greet my birds and say the same phrases to them when I do things every day, so they tend to pick them up eventually. If you get upset or aggravated or frustrated at her for saying the same word over and over again, she gets a reaction and you are only reinforcing that word. My amazon will pick things up quicker I say if it is loud and have a lot of fluctuation in the phrase or word. She loves to yell, OH MY GOD! and then laugh loudly. She also likes to scream like I tend to if I drop something or trip...
Give it time, be patient and she will relax and open up when SHE is ready. Gosh!You've only had her 3 weeks, she isn't even settled in yet......you are expecting too much, too fast, it could take her up to a year with you to totally and completely trust you and feel at home IMP.