First, I'm truly sorry about the loss of your first grey. It must have been devastating to have lost him. I understand WHY this would make you so nervous about your second one. But please try to relax and not worry and study so hard. If you are "looking" for something that may be wrong with your baby, she may pick up on your anxiety and fears about her welfare and get nervous. Greys are very telepathic and pick up on each others' feelings, including their humans. She would not understand exactly what you're thinking, but could pick up on YOUR nervousness about "doing what's right" and feel nervous herself that something is wrong. So, please try to relax.
Wild caught greys are no longer sold in America since it has been against the law to sell them since 1993... that is, unless you had an older one that was imported to the US before that time. Therefore, I'm assuming that you are from out of the country. Therefore, I'm also assuming that this precious baby now in your life is not a socialized baby grey. If this is true, the first thing you need to do is to establish a strong of bond of trust with this baby. Actually, even if it is socialized, the bond of trust is always the most important first step in a relationship.
It is difficult to write to you about the nipping and growling problem without more information. Please submit another post and explain to us what the situation is like. Please describe what happens. What are you doing with her before she growls and/or nips? Please describe the situation in detail and we will be better able to help you.
Usually if a baby is nipping and growling, it is feeling fear of something that you are doing. Step back and move more slowly with her to build that trust relationship first. That can start with such simple things as you spending time with her by the cage, talking to her, reading to her and singing to her.
Looking forward to hearing from you again.