How grown-up were you at the mental age of 10?
Seven was 6 years old when assimilated, and lived 4 years of her life as a former drone. You can't expect her to suddenly make up for all the missed emotional and psychological development she would normally have gone through, in such a short time.
(I'm on your side.)
1. I think she was 8.
2. She was awake and watching the whole time for the first twenty years complicit and happy.
3. While regenerating during the first 20 years, she hung out rounding off her subconscious maturity in Unimatrix Zero, that she was never quite able to access till the end, which was a clear line of before she was a woman and after she was a girl.
4. It's clear she was (literally and non pejoratively) retarded since every week she would have to quirt through the same trial or crucible, and not learn a retainable damn thing.