My Dearest Daughter

Connie is my dearest daughter. She is now 16 years old and taller,I left out "bigger," because in English saying that a girl is bigger can be seen as a bit insulting haha smarter and more beautiful than me. As I watch her develop from my little girl into a young lady I'm filled with bittersweet feelings I thought "bittersweet" here is more descriptive due to what you say right afterward ;a clear sense of pride and a vague feeling of loss.
Compared with other girls of her age in China she's rather independent and always a straight-A student, which saves me a lot of trouble. Now she almost does all the shopping for herself but it's a bit funny I can't remember clearly when she began doing this, maybe 2 years ago. She is an only child so my husband and I always satisfy her as long as her requirements are reasonable. Growing in a rich and comfortable environment she is confident, smart and knowledgeable. I envy her and am proud of her.

She used to have a lot to talk about with me, but now she seems to enjoy chatting with her friends more. When I was in other countries or cities I would eagerly call her expecting to talk for a while; however, she sometimes would cut me short, which really made me feel lost. Where is my darling girl? I comfort myself with the thought that she's grown up and going through a rebellious phase. Somehow from the bottom of my heart I still have a nameless feeling of loss.

You're English is really great! I just reworded some things to make it flow a little better and sound more natural to a native English speaker but it was almost perfect. I would suggest you be careful about putting to many commas, though. Awesome!

my dearest daughter My Dearest Daughter

Connie is my dearest daughter, who is now 16 years old. She is taller, bigger, smarter and more beautiful than I me. Watching her developing from my little girl into a young lady, I'm filled with some kind of complicated feeling, a clear sense of pride and a vague feeling of loss.
(This sentence is right, but I think it sounds better like... "As I have watched her develop from a little girl into a young lady, I am filled with complicated feelings such as a clear sense of pride and a vague feeling of loss")

Compared with other girls of her age in China, she's rather independent and always an all-A student in school, which has saved me a lot of trouble. Now she almost does does almost all the shopping for herself. but It's a bit funny, but I can't remember clearly when she began shopping for herself, maybe 2 years ago. She is the only child, so my husband and I always satisfy her as long as her requirements are reasonable. Growing in a rich and comfortable environment, she is confident, smart and knowledgeable. I envy her and am proud of her.

She used to have a lot to talk about with me. But now she seems more to like to chat with her friends more. When I was in other countries or other cities, I eagerly called her expecting to tell her a lot, but she sometimes just cut me short, which really made me feel lost. Where is my darling girl? I comfort myself by telling myself that she's grown up and a teenager is always rebellious. Somehow, from the bottom of my heart I still have a nameless feeling of loss.